全文获取类型
收费全文 | 20616篇 |
免费 | 45篇 |
国内免费 | 72篇 |
专业分类
系统科学 | 62篇 |
丛书文集 | 127篇 |
教育与普及 | 55篇 |
理论与方法论 | 64篇 |
现状及发展 | 8725篇 |
研究方法 | 939篇 |
综合类 | 10448篇 |
自然研究 | 313篇 |
出版年
2013年 | 117篇 |
2012年 | 290篇 |
2011年 | 606篇 |
2010年 | 133篇 |
2008年 | 320篇 |
2007年 | 398篇 |
2006年 | 348篇 |
2005年 | 400篇 |
2004年 | 383篇 |
2003年 | 362篇 |
2002年 | 365篇 |
2001年 | 692篇 |
2000年 | 696篇 |
1999年 | 486篇 |
1994年 | 312篇 |
1992年 | 446篇 |
1991年 | 352篇 |
1990年 | 396篇 |
1989年 | 357篇 |
1988年 | 357篇 |
1987年 | 368篇 |
1986年 | 337篇 |
1985年 | 477篇 |
1984年 | 345篇 |
1983年 | 298篇 |
1982年 | 287篇 |
1981年 | 260篇 |
1980年 | 290篇 |
1979年 | 685篇 |
1978年 | 529篇 |
1977年 | 480篇 |
1976年 | 416篇 |
1975年 | 459篇 |
1974年 | 494篇 |
1973年 | 463篇 |
1972年 | 528篇 |
1971年 | 565篇 |
1970年 | 695篇 |
1969年 | 562篇 |
1968年 | 579篇 |
1967年 | 536篇 |
1966年 | 519篇 |
1965年 | 336篇 |
1959年 | 174篇 |
1958年 | 317篇 |
1957年 | 210篇 |
1956年 | 175篇 |
1955年 | 152篇 |
1954年 | 141篇 |
1948年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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
82.
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
83.
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
84.
D. V. Amin R. B. Doctor A. O. Girdhar U. H. Shah 《Cellular and molecular life sciences : CMLS》1980,36(12):1410-1411
Summary Prostaglandin (PG) release was measured from the isolated perfused rabbit heart. The effects of -adrenergic stimulation and blockade suggest that PG synthesis is regulated in part by adrenergic mechanisms. 相似文献
85.
Summary The C-terminal amino acid sequences of human and of porcine antithrombin III have been determined as Gly-Arg-Val-Ala-Asn-Pro-Cys-Val-Lys and Gly-Arg-Val-Ala-Asn-Pro-Cys, respectively. These sequences are highly homologous with the C-terminal sequence of human -1-proteinase inhibitor. 相似文献
86.
G. B. Glavin 《Cellular and molecular life sciences : CMLS》1980,36(1):79-80
Summary Rats given aluminium hydroxide after cold-restraint stress but before the post-stress delay period, ulcerated significantly less severely and less frequently than rats given the drug before cold-restraint stress or those given water at either time period. Both aluminium hydroxide treated groups exhibited less ulceration than non-drug groups. These data suggest profound parasympathetic and hence, gastric acid, involvement in restraint delay-induced ulceration in rats. 相似文献
87.
T. Stojanovié B. M. Djuričić B. B. Mršulja 《Cellular and molecular life sciences : CMLS》1980,36(12):1348-1350
Summary The activity of (Na++K+)-ATPase and acetylcholine esterase were folloed in rat brain cerebral cortex, caudate, thalamus, hippocampus and medulla after i.v. administration of physostigmine. Both enzymes were found to be inhibited in a dose-dependent manner. The most pronounced inhibition of (Na++K+)-ATPase was found in caudate. where the highest activity of acetylcholine esterase is found.These studies were supported by a grant from the Union of Science of Republic Serbia, No. 40404-14. 相似文献
88.
Summary Contrary to Srdi and Gloor's report, we find crystal cells (cc) in the lymph glands ofD. melanogaster larvae; the size and number of inclusions in the cc cannot be used to distinguish the 2 sibling species,D. melanogaster andD. simulans; cc in the hemocoel are not phagocytic cells; the surface properties of the lamellocytes are consistent with their derivation from plasmatocytes and not cc.Supported by grant No. CA16619 awarded by the National Cancer Institute, DHEW, USPHS. 相似文献
89.
T. Kuroiwa S. Nishibayashi S. Kawano T. Suzuki 《Cellular and molecular life sciences : CMLS》1981,37(9):969-971
Summary DNA-containing areas in various phages (T4, , T7 and 29) could be observed at the light microscopic level using ethidium bromide epi-fluorescent microscopy. The fluorescent intensity per phage was in linear proportion to the DNA content in each phage.Acknowledgements. This work was supported in part by the grant No. 521708 and No. 511212 from the Japan Ministry of Education, Science and Culture. 相似文献
90.
Y. Kakiuchi G. M. Hughes T. Arai M. Horimoto Y. Kikuchi T. Koyama 《Cellular and molecular life sciences : CMLS》1981,37(4):376-377
Summary A needle type of colloid osmometer has been devised with special attachments which made it useable with 3-l samples. It has been used in oncometry of fresh water teleosts to give the following results: 5.1±1.0 mm Hg for goldfish, 5.2±0.71 mm Hg for carp, and 14.3±0.75 mm Hg for eel.This study was supported in part by Research Grant 387036 from the Ministry of Education of Japan.invited to National Institute of Physiological Sciences, Okazaki, Japan. 相似文献