首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4038篇
  免费   17篇
  国内免费   32篇
系统科学   65篇
丛书文集   87篇
教育与普及   143篇
理论与方法论   9篇
现状及发展   250篇
研究方法   556篇
综合类   2976篇
自然研究   1篇
  2021年   6篇
  2019年   5篇
  2017年   4篇
  2016年   4篇
  2014年   6篇
  2012年   303篇
  2011年   346篇
  2010年   81篇
  2009年   17篇
  2008年   279篇
  2007年   347篇
  2006年   300篇
  2005年   320篇
  2004年   314篇
  2003年   300篇
  2002年   261篇
  2001年   225篇
  2000年   340篇
  1999年   85篇
  1998年   14篇
  1997年   7篇
  1996年   11篇
  1995年   8篇
  1994年   9篇
  1993年   16篇
  1992年   6篇
  1991年   16篇
  1990年   18篇
  1989年   17篇
  1988年   16篇
  1987年   15篇
  1986年   19篇
  1985年   17篇
  1984年   19篇
  1983年   22篇
  1982年   24篇
  1981年   24篇
  1980年   6篇
  1979年   11篇
  1978年   8篇
  1971年   10篇
  1970年   21篇
  1966年   6篇
  1959年   30篇
  1958年   38篇
  1957年   34篇
  1956年   20篇
  1955年   27篇
  1954年   21篇
  1948年   12篇
排序方式: 共有4087条查询结果,搜索用时 0 毫秒
1.
这两本书是法律心理学。应用心理学之中,例如教育心理学(Educational Psychology);商业心理学(Business Psychology),在英美早已成为常用的专门名词。法律心理学,这个名称近年来在英文杂志里边虽已惯用,而专书仍属罕见-就我所知除Bose’s Introduction to Juristic Psychology, 1917及Brown’s LegalPsychology,1826两书以外,就有这两本专著。教育心理学,商业心理学。这些名称在中文里边近年来虽已沿用;而法律心理学却尚未经见。至於这门学问,在我们中国不但研究法律的人向不留心,恐怕研究心理学的人亦很少注意。 第一本书的著作者Burt…  相似文献   
2.
Auditory neuropathy is a particular type of hearing impairment in which neural transmission of the auditory signal is impaired, while cochlear outer hair cells remain functional. Here we report on DFNB59, a newly identified gene on chromosome 2q31.1-q31.3 mutated in four families segregating autosomal recessive auditory neuropathy. DFNB59 encodes pejvakin, a 352-residue protein. Pejvakin is a paralog of DFNA5, a protein of unknown function also involved in deafness. By immunohistofluorescence, pejvakin is detected in the cell bodies of neurons of the afferent auditory pathway. Furthermore, Dfnb59 knock-in mice, homozygous for the R183W variant identified in one DFNB59 family, show abnormal auditory brainstem responses indicative of neuronal dysfunction along the auditory pathway. Unlike previously described sensorineural deafness genes, all of which underlie cochlear cell pathologies, DFNB59 is the first human gene implicated in nonsyndromic deafness due to a neuronal defect.  相似文献   
3.
Collagen VI is an extracellular matrix protein that forms a microfilamentous network in skeletal muscles and other organs. Inherited mutations in genes encoding collagen VI in humans cause two muscle diseases, Bethlem myopathy and Ullrich congenital muscular dystrophy. We previously generated collagen VI-deficient (Col6a1-/-) mice and showed that they have a muscle phenotype that strongly resembles Bethlem myopathy. The pathophysiological defects and mechanisms leading to the myopathic disorder were not known. Here we show that Col6a1-/- muscles have a loss of contractile strength associated with ultrastructural alterations of sarcoplasmic reticulum (SR) and mitochondria and spontaneous apoptosis. We found a latent mitochondrial dysfunction in myofibers of Col6a1-/- mice on incubation with the selective F1F(O)-ATPase inhibitor oligomycin, which caused mitochondrial depolarization, Ca2+ deregulation and increased apoptosis. These defects were reversible, as they could be normalized by plating Col6a1-/- myofibers on collagen VI or by addition of cyclosporin A (CsA), the inhibitor of mitochondrial permeability transition pore (PTP). Treatment of Col6a1-/- mice with CsA rescued the muscle ultrastructural defects and markedly decreased the number of apoptotic nuclei in vivo. These findings indicate that collagen VI myopathies have an unexpected mitochondrial pathogenesis that could be exploited for therapeutic intervention.  相似文献   
4.
Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements.  相似文献   
5.
A new microscopic principle   总被引:2,自引:0,他引:2  
GABOR D 《Nature》1948,161(4098):777
  相似文献   
6.
7.
8.
9.
The NOTCH4 gene was recently reported to be associated with schizophrenia based on TDT analysis of 80 British trios. The strongest evidence for association derived from two microsatellites. We genotyped both loci in a large sample of unrelated Scottish schizophrenics and controls, but failed to replicate the reported association, finding instead that each putative schizophrenia-associated allele had a somewhat lower frequency in schizophrenics than in controls.  相似文献   
10.
Alexander disease is a rare disorder of the central nervous system of unknown etiology. Infants with Alexander disease develop a leukoencephalopathy with macrocephaly, seizures and psychomotor retardation, leading to death usually within the first decade; patients with juvenile or adult forms typically experience ataxia, bulbar signs and spasticity, and a more slowly progressive course. The pathological hallmark of all forms of Alexander disease is the presence of Rosenthal fibers, cytoplasmic inclusions in astrocytes that contain the intermediate filament protein GFAP in association with small heat-shock proteins. We previously found that overexpression of human GFAP in astrocytes of transgenic mice is fatal and accompanied by the presence of inclusion bodies indistinguishable from human Rosenthal fibers. These results suggested that a primary alteration in GFAP may be responsible for Alexander disease. Sequence analysis of DNA samples from patients representing different Alexander disease phenotypes revealed that most cases are associated with non-conservative mutations in the coding region of GFAP. Alexander disease therefore represents the first example of a primary genetic disorder of astrocytes, one of the major cell types in the vertebrate CNS.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号