全文获取类型
收费全文 | 31086篇 |
免费 | 76篇 |
国内免费 | 93篇 |
专业分类
系统科学 | 257篇 |
丛书文集 | 562篇 |
教育与普及 | 72篇 |
理论与方法论 | 97篇 |
现状及发展 | 13503篇 |
研究方法 | 1204篇 |
综合类 | 15065篇 |
自然研究 | 495篇 |
出版年
2013年 | 205篇 |
2012年 | 405篇 |
2011年 | 902篇 |
2010年 | 169篇 |
2008年 | 463篇 |
2007年 | 529篇 |
2006年 | 533篇 |
2005年 | 539篇 |
2004年 | 532篇 |
2003年 | 538篇 |
2002年 | 454篇 |
2001年 | 934篇 |
2000年 | 926篇 |
1999年 | 575篇 |
1992年 | 559篇 |
1991年 | 475篇 |
1990年 | 528篇 |
1989年 | 451篇 |
1988年 | 495篇 |
1987年 | 510篇 |
1986年 | 444篇 |
1985年 | 648篇 |
1984年 | 471篇 |
1983年 | 401篇 |
1982年 | 363篇 |
1981年 | 358篇 |
1980年 | 463篇 |
1979年 | 971篇 |
1978年 | 795篇 |
1977年 | 757篇 |
1976年 | 666篇 |
1975年 | 734篇 |
1974年 | 898篇 |
1973年 | 809篇 |
1972年 | 856篇 |
1971年 | 969篇 |
1970年 | 1263篇 |
1969年 | 1006篇 |
1968年 | 935篇 |
1967年 | 930篇 |
1966年 | 844篇 |
1965年 | 588篇 |
1964年 | 151篇 |
1959年 | 352篇 |
1958年 | 568篇 |
1957年 | 420篇 |
1956年 | 372篇 |
1955年 | 315篇 |
1954年 | 326篇 |
1948年 | 246篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
211.
B. Stankiewicz-Choroszucha J. Górski 《Cellular and molecular life sciences : CMLS》1978,34(3):357-358
Summary It was shown in the rat that mobilization of intramuscular triglyceride during exercise is controlled by the adrenergic system.Acknowledgments. The work was supported by the Polish Academy of Sciences, grant No. 10.4.2.01.3.2. 相似文献
212.
B. Jazdowska-Zagrodzińska B. Matuszewski 《Cellular and molecular life sciences : CMLS》1978,34(6):777-778
Summary Lamellar structures in oogonial and spermatogonial cells of gall midges were found to form a complicated system of intranuclear compartments inside which all heteropycnotic chromosomes present in the germ-line cells of these insects are located. In this way, the heteropycnotic S-chromosomes are separated by the nuclear lamellae from the remaining, decondensed chromosomes (E-chromosomes) of the interphase germ-line nucleus.This investigation was supported in part under Contract DPKBN/52/76-II.1.3.10. with the Polish Academy of Sciences. 相似文献
213.
Summary The seedling growth ofBrassica campestris var.varuna, has been studied, as affected by water-stress and gibberellin treatments. A boost in the net GA response due to water-stress, has been observed. Thus presence of GA can overcome the water-stress effects.Publication No. 26 from Dept of Biosciences, Himachal Pradesh University, Simla. Authors are grateful to CSIR, New Delhi, for JRF to SB. 相似文献
214.
The effect ofγ-irradiation on soil enzyme stability 总被引:1,自引:0,他引:1
R. G. Burns Lindsay J. Gregory G. Lethbridge N. M. Pettit 《Cellular and molecular life sciences : CMLS》1978,34(3):301-302
Summary Arylsulphatase, -1,3 glucanase, phosphatase and urease responded differently to -irradiation (5–50 Mrad) in air-dried and moist soils. In all instances phosphatase was the most stable. The variability between enzymes may be due to inherent biochemical and stuctural characteristics or to their location within the soil microenvironment.Supported by a grant from the NERC. 相似文献
215.
Large-scale purification of hepatitis B surface antigen using affinity chromatography 总被引:2,自引:0,他引:2
A. R. Neurath A. M. Prince J. Giacalone 《Cellular and molecular life sciences : CMLS》1978,34(3):414-415
Summary Large-scale purification of hepatitis B surface antigen, applicable to the preparation of potential vaccines for prevention of hepatitis B, is described. The method involves the following steps: precipitation of serum with polyethylene glycol 6000, affinity chromatography on concanavalin A-Sepharose and on -aminononyl-Sepharose, and isopycnic centrifugation.This study was supported by grant 09011 from the National Heart, Lung and Blood Institute. We thank Dr. B. Hollinger for testing HBsAg samples by a complement fixation test. 相似文献
216.
M Debray-Sachs M Dy H Aurengo B Descamps 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1978,286(2):249-252
CBA Mice were immunized by two intraperitoneal injections of 30 X 10(6) DBA/2 or C57BL/6 spleen cells at days--12 and--2. Peritoneal cell population was obtained at day zero by washing the peritoneal cavity of Mice. Adherent cells were then separated using a 2 hrs. incubation in "Falcon" plates followed by washing. This macrophage-rich peritoneal cell population was found nonspecifically cytotoxic against 51Cr labeled tumoral target cells: P815 X DBA/2 mastocytoma cells, EL4 X C57BL/L lymphoma cells and spontaneous lymphoma AKR cells (same H--2k as CBA). This adherent peritoneal cell cytoxicity was demonstrated after 24 hrs. incubation with the target cells. It was found in nonspecific combination as well as when using target cells syngeneic to the donor. These findings suggest that adherent peritoneal cell cytotoxicity could be at least partly due to macrophages and result from factor (s) released by sensitized lymphocytes in vivo in the same way as has been previously demonstrated in vitro. 相似文献
217.
J Montreuil B Fournet G Spik G Strecker 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1978,287(8):837-840
The construction of molecular models for the human serotransferrin glycans shows that they present one compact section linked to the protein and constituted by the pentasaccharide alpha-Man-(1 leads to 3)-[alpha-Man-(1 leads to 6)]-beta-Man-(1 leads to 4)-beta-GlcNAc-(1 leads to 4)-beta-GlcNAc-(1 leads to)-Asn to which are attached two "antennae" consisting of the trisaccharide alpha-NANA-(2 leads to 6)-beta-Gal-(1 leads to 4)-beta-GlcNAc. The trisaccharide sequence beta-Man-(1 leads to 4)-beta-GlcNAc-(1 leads to 4)-beta-GlcNAc adopts a flat and rigid conformation, stabilised by hydrogen bonds. In contrast, the sequence alpha-NANA-(1 leads to 6)-beta-Gal-(1 leads to 4)-beta-GlcNAc-(1 leads to 2)-alpha-Man takes up a helical configuration. The two "antennae" can be disposed on the pentasaccharide core to give two possible configurations, one Y-shaped and the other T-shaped. In both cases, the general conformation of the glycans is perfectly compatible with their postulated role as a recognition signal. 相似文献
218.
R Lang 《Experientia》1978,34(4):500-501
Moxnidazole [3-(5-nitrol-1-methyl-2-imidazolyl)-methyleneamino-5-morpholinomethyl-2-oxazolidinone, HCl], known to be mutagenic in microbial tests and Drosophila, induced genetic alterations in somatic cells of mice. Ethyl methanesulfonate (EMS) served as positive control. 相似文献
219.
Rana esculenta (L.), kept under natural conditions, show almost constant body weights in the annual cycle. Fat body weight, however, has a distinct maximum in October decreasing continuously to a May minimum which is also evident in the fat body index. The triglyceride and protein contents show the same course. Suprisingly high amounts of glycogen are found, which reach a maximum in August. 相似文献
220.
At ambient temperatures (Ta) of both 8 and 22 degrees C, intraventricular administration of TRH (10-80 microgram) produced a dose-dependent hypothermia in rats. The hypothermia was due to both decreased metabolic heat production and cutaneous vasodilatation. In contrast, at 30 degrees C Ta, TRH increased metabolic heat production (due to behavioral excitation) and led to hyperthermia. 相似文献