全文获取类型
收费全文 | 9993篇 |
免费 | 1020篇 |
国内免费 | 6篇 |
出版年
2022年 | 59篇 |
2021年 | 134篇 |
2020年 | 91篇 |
2019年 | 145篇 |
2018年 | 138篇 |
2017年 | 118篇 |
2016年 | 201篇 |
2015年 | 377篇 |
2014年 | 410篇 |
2013年 | 466篇 |
2012年 | 607篇 |
2011年 | 589篇 |
2010年 | 386篇 |
2009年 | 374篇 |
2008年 | 519篇 |
2007年 | 520篇 |
2006年 | 482篇 |
2005年 | 434篇 |
2004年 | 457篇 |
2003年 | 417篇 |
2002年 | 348篇 |
2001年 | 209篇 |
2000年 | 171篇 |
1999年 | 175篇 |
1998年 | 157篇 |
1997年 | 112篇 |
1996年 | 112篇 |
1995年 | 132篇 |
1994年 | 112篇 |
1993年 | 96篇 |
1992年 | 137篇 |
1991年 | 116篇 |
1990年 | 134篇 |
1989年 | 112篇 |
1988年 | 105篇 |
1987年 | 102篇 |
1986年 | 90篇 |
1985年 | 80篇 |
1984年 | 101篇 |
1983年 | 83篇 |
1982年 | 86篇 |
1981年 | 80篇 |
1980年 | 68篇 |
1979年 | 75篇 |
1978年 | 52篇 |
1977年 | 58篇 |
1976年 | 53篇 |
1975年 | 53篇 |
1974年 | 73篇 |
1973年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
A C Srivastava A J Pinching M W Adler R Robertson R Higgs 《BMJ (Clinical research ed.)》1987,294(6570):495-496
Dr A C Srivastava has written to us to describe a case that raises the suggestion that people infected with the human immuno-deficiency virus (HIV) should carry identity cards. We asked two physicians, a general practitioner working with patients with the acquired immune deficiency syndrome (AIDS), and a general practitioner with a special interest in medical ethics to respond to the broad issues raised by Dr Srivastava''s letter. 相似文献
4.
The 30-Base-Pair Deletion in Chinese Variants of the Epstein-Barr Virus LMP1 Gene Is Not the Major Effector of Functional Differences between Variant LMP1 Genes in Human Lymphocytes 总被引:7,自引:3,他引:4
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rowena J. Johnson Maria Stack Sheila A. Hazlewood Matthew Jones Colin G. Blackmore Li-Fu Hu Martin Rowe 《Journal of virology》1998,72(5):4038-4048
One group of sequence variants of Epstein-Barr virus is characterized by a 10-amino-acid deletion within the CTAR-2 functional domain of the latent membrane protein, LMP1. A role for this deletion in enhancing the tumorigenicity of the viral oncogene in rodent fibroblasts was recently demonstrated. We examined the effect of this deletion upon LMP1 function in four human lymphoid cell lines by using three natural variants of LMP1: the prototype B95.8 gene and the CAO and AG876 genes, both of which have codons 343 to 352 of the B95.8-LMP1 deleted. These experiments revealed that LMP1-mediated upregulation of CD40 and CD54 was markedly impaired (by 60 to 90%) with CAO-LMP1 compared with B95.8-LMP1. In contrast, the function of AG876-LMP1 was indistinguishable from that of B95.8-LMP1 in two lines and was only slightly impaired in the other two lines. Activation of NF-κB by CAO-LMP1 was not impaired in any of the lines; rather, activation of an NF-κB reporter by CAO-LMP1 was consistently about twofold greater than the activation with B95.8- or AG876-LMP1. Therefore, while the CAO-LMP1 is functionally distinct from the prototype B95.8-LMP1 in human lymphocytes, the 10-amino-acid deletion appears not to be directly responsible. This conclusion was confirmed by using a B95.8-LMP1 mutant with codons 343 to 352 deleted and chimerae of CAO- and B95.8-LMP1 in which the CTAR-2 domains of these genes were exchanged. Sequences outside the CTAR-2 domain were implicated in the distinct functional characteristics of CAO-LMP1 in human lymphoid cells. 相似文献
5.
6.
During the process optimisation of glucoamylase production by Aspergillus awamori, cell morphology was controlled at such a state that spore aggregation was completely prevented. Samples from five fermentations on complex media using either glucose or starch as carbon source were characterised with a Bohlin CS rheometer. The experimental data were conveniently described in terms of the power law model. 相似文献
7.
8.
Colin K.W. Watts Robert L. Sutherland 《Biochemical and biophysical research communications》1984,120(1):109-115
Saturation and competitive binding analyses demonstrated the presence of a high affinity (KD = 0.92 nM), specific antiestrogen binding site (AEBS) in rat liver microsomes and at least 75% of total liver AEBS was recovered in this fraction. When microsomes were further separated into smooth and rough fractions, AEBS was concentrated in the latter. Subsequent dissociation of ribosomes from the rough membranes revealed that AEBS was associated with the membrane and not the ribosomal fraction. Antiestrogen binding activity could not be extracted from membranes with 1 M KCl or 0.5 M acetic acid but could be solubilized with sodium cholate. These data indicate that AEBS is an integral membrane component of the rough microsomal fraction of rat liver. 相似文献
9.
Eileen M. Proctor Judith L. Isaac-Renton William B. Robertson William A. Black 《CMAJ》1985,133(9):876-878
A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes. 相似文献
10.
Estimation of chitin deposition in the pupal and adult cuticles of adult Drosophila melanogaster during the pupal period is described. The timing of the periods of chitin deposition is compared with that deduced by previous workers using electron microscopy. The hypothesis that lethalcryptocephal mutant homozygotes are unable to evert their cephalic complexes at pupation because of excess chitin deposition is examined. The data obtained show no evidence that the mutation has any effect on chitin deposition. 相似文献