全文获取类型
收费全文 | 1505篇 |
免费 | 198篇 |
国内免费 | 1篇 |
出版年
2021年 | 33篇 |
2020年 | 18篇 |
2019年 | 15篇 |
2018年 | 28篇 |
2017年 | 24篇 |
2016年 | 43篇 |
2015年 | 63篇 |
2014年 | 69篇 |
2013年 | 75篇 |
2012年 | 114篇 |
2011年 | 97篇 |
2010年 | 71篇 |
2009年 | 58篇 |
2008年 | 67篇 |
2007年 | 89篇 |
2006年 | 72篇 |
2005年 | 53篇 |
2004年 | 65篇 |
2003年 | 65篇 |
2002年 | 43篇 |
2001年 | 29篇 |
2000年 | 24篇 |
1999年 | 26篇 |
1998年 | 25篇 |
1997年 | 18篇 |
1995年 | 18篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 15篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1986年 | 19篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 19篇 |
1976年 | 14篇 |
1975年 | 11篇 |
1973年 | 14篇 |
1972年 | 11篇 |
1968年 | 13篇 |
1966年 | 11篇 |
排序方式: 共有1704条查询结果,搜索用时 171 毫秒
1.
2.
3.
4.
5.
A new algorithm is proposed to determine the type-II restrictionendonucleases' recognition site knowing the digested DNA sequenceand fragment lengths in an actual case. The algorithm is implementedfor the Commodore 64 microcomputer.
Received on January 6, 1987; accepted on June 19, 1987 相似文献
6.
Adding noise to a visual image makes object recognition more effortful and has a widespread effect on human electrophysiological responses. However, visual cortical processes directly involved in handling the stimulus noise have yet to be identified and dissociated from the modulation of the neural responses due to the deteriorated structural information and increased stimulus uncertainty in the case of noisy images. Here we show that the impairment of face gender categorization performance in the case of noisy images in amblyopic patients correlates with amblyopic deficits measured in the noise-induced modulation of the P1/P2 components of single-trial event-related potentials (ERP). On the other hand, the N170 ERP component is similarly affected by the presence of noise in the two eyes and its modulation does not predict the behavioral deficit. These results have revealed that the efficient processing of noisy images depends on the engagement of additional processing resources both at the early, feature-specific as well as later, object-level stages of visual cortical processing reflected in the P1 and P2 ERP components, respectively. Our findings also suggest that noise-induced modulation of the N170 component might reflect diminished face-selective neuronal responses to face images with deteriorated structural information. 相似文献
7.
8.
Rayna Rapp 《Medical anthropology quarterly》2001,15(4):466-477
This article tracks the growth of medical anthropology in the United States in the decades since the 1970s, as it has intersected the expansion of feminist activism and scholarship. I argue that feminist attention to embodied inequalities quickly focused on reproduction as a site of investigation and intervention. Medical anthropology has benefited from feminist concern with stratified reproduction, especially its interrogation of nonnormative and stigmatized fertility and childbearing. When reproduction becomes problematic, it provides a lens through which cultural norms, struggles, and transformations can be viewed. Examples drawn from prenatal diagnosis are particularly revelatory of the diverse interests and stakes we all hold in reproduction. 相似文献
9.
Role of c-myc and other genes in interleukin 2 regulated CT6 T lymphocytes and their malignant variants 总被引:6,自引:0,他引:6
J L Cleveland U R Rapp W L Farrar 《Journal of immunology (Baltimore, Md. : 1950)》1987,138(10):3495-3504
The cloned murine cytotoxic T cell line CT6 solely requires interleukin 2 (IL 2) for viability and cell cycle progression. Treatment of G arrested cultures of CT6 cells with recombinant IL 2 induces the rapid sequential expression of the nuclear proto-oncogenes c-fos, c-myc, and c-myb but does not affect the expression of several cytosolic or membrane-associated proto-oncogenes. A comparison of early genes induced by growth factor treatment of quiescent NIH/3T3 fibroblasts and CT6 cells demonstrated that only c-fos and c-myc induction is shared in the two different lineages. Factor-independent lines derived from CT6 cells show no mitogenic response to IL 2, yet binding of IL 2 with its receptor in the cells was capable of inducing the expression of c-fos and c-myc. In factor-independent cell lines, c-myc was uniformly expressed at high constitutive levels, suggesting that c-myc abrogates growth factor requirements of these cells. The levels of c-myc expression in the factor-independent lines was not due to an autocrine production of IL 2 but may be a consequence of constitutively activated IL 2 receptors. 相似文献
10.
Judit Kapocsi George T. Somogyi Nandor Ludvig Peter Serfozo Laszlo G. Harsing Jr. Russell J. Woods E. Sylvester Vizi 《Neurochemical research》1987,12(2):141-147
Neurochemical and pharmacological evidence has been obtained that noradrenergic varicosities (in mouse and rat vas deferens) and cholinergic varicosities (in the Auerbach's plexus) contain heterogenous alpha2-adrenoceptors through which the release of [3H]noradrenaline and [3H]acetylcholine can be modulated. The quantitative data also support the hypothesis that different noradrenaline and xylazine sensitive alpha2-adrenoceptors are present prejunctionally in the vas deferens and Auerbach's plexus preparations. Prazosin, although it has a presynaptic inhibitory effect on alpha2-adrenoceptors of noradrenergic axon terminals, has no effect on cholinergic axon terminals. These data suggest that there are two different types of alpha2-adrenoceptors at the presynaptic axon terminals.Special Issue Dedicated to Dr. Abel Lajtha 相似文献