全文获取类型
收费全文 | 14443篇 |
免费 | 1247篇 |
国内免费 | 5篇 |
出版年
2023年 | 43篇 |
2022年 | 62篇 |
2021年 | 228篇 |
2020年 | 113篇 |
2019年 | 184篇 |
2018年 | 195篇 |
2017年 | 174篇 |
2016年 | 382篇 |
2015年 | 581篇 |
2014年 | 757篇 |
2013年 | 865篇 |
2012年 | 1097篇 |
2011年 | 1075篇 |
2010年 | 709篇 |
2009年 | 631篇 |
2008年 | 902篇 |
2007年 | 872篇 |
2006年 | 841篇 |
2005年 | 769篇 |
2004年 | 748篇 |
2003年 | 758篇 |
2002年 | 704篇 |
2001年 | 145篇 |
2000年 | 139篇 |
1999年 | 169篇 |
1998年 | 222篇 |
1997年 | 147篇 |
1996年 | 126篇 |
1995年 | 144篇 |
1994年 | 115篇 |
1993年 | 134篇 |
1992年 | 137篇 |
1991年 | 99篇 |
1990年 | 87篇 |
1989年 | 82篇 |
1988年 | 71篇 |
1987年 | 55篇 |
1986年 | 74篇 |
1985年 | 69篇 |
1984年 | 84篇 |
1983年 | 48篇 |
1982年 | 65篇 |
1981年 | 50篇 |
1980年 | 45篇 |
1979年 | 53篇 |
1978年 | 41篇 |
1977年 | 54篇 |
1976年 | 36篇 |
1974年 | 41篇 |
1973年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Christine C. Berte Nobuyuki Tanigaki Roberto Tosi Jack Gorski Bernard Mach 《Immunogenetics》1988,27(3):167-173
HLA class 11 molecules were isolated from mouse L cells transfected with a DR
gene and an allele, 52a, of locus DR
III from an HLA-homozygous cell line, AVL, of the DR3 haplotype. The isolated molecules were found to possess a new allospecificity, named TR81. This specificity behaved allelic to the previously described DR
III locus. The TR81 specificity was also present on the DR
I gene product of the DR3 haplotype. The nucleotide sequence of the gene encoding TR81 differs from TR81-negative DR
genes of the DRw52 family in only two codons, both located in the regions known to be involved in a gene conversion event. Consequently, the following conclusions can be formulated. (a) TR81 is a bi-locus specificity and allelic to TR22 only in its DR
III locus localization. (b) The TR81 specificity is the phenotypic counterpart of the gene conversion event which led to the generation of the DR
I gene of the DR3 haplotype. (c) One or both individual amino acid substitutions in the first domain of the DR
chain are responsible for the TR81 allospecificity. (d) Since TR81 is expressed on the DR
I chain of the DR3 haplotype, it is possible that TR81 and DR3 represent the same serological specificity. 相似文献
52.
Jürgen M. Schmitt Christine Michalowski Hans J. Bohnert 《Photosynthesis research》1988,17(1-2):159-171
Mesembryanthemum crystallinum responds to high salinity in the soil by shifting the mode of carbon assimilation from the C3 mode to Crassulacean acid metabolism (CAM). Several enzymes of carbon metabolism have increased apparent activities in the CAM mode, including phosphoenolpyruvate carboxylase (PEPcase) and pyruvate orthophosphate dikinase (PPDK). We have identified cDNA clones for PEPcase and PPDK by immunological screening of a cDNA library constructed in the protein expression vector lambda gt11. The clones were characterized by immunoblotting and RNA blotting techniques. RNA blotting showed that during CAM induction the steady-state level of mRNAs for both PEP case and PPDK increased.Abbreviations IPTG
isopropyl thiogalactoside
- PEP
phosphoenolpyruvate
- PEPcase
phosphoenolpyruvate carboxylase
- PPDK
pyruvate orthophosphate dikinase
- Xgal-5
bromo-4-chloro-3-indolyl-beta-D-galactopyranoside 相似文献
53.
Cytoplasmic Poly(ADP-Ribose) Polymerase Associated with Free Messenger Ribonucleoprotein Particles in Rat Brain 总被引:1,自引:0,他引:1
Poly(ADP-ribose) polymerase associated with free cytoplasmic messenger ribonucleoprotein particles (free mRNP particles) carrying messenger RNA has been characterized in rat brain. There were first-order kinetics for NAD with an apparent Km for NAD of 90.5 +/- 0.70 microM and Vmax of 19.7 +/- 2.8 pmol ADP-ribose incorporated min-1 mg protein-1. Five poly(ADP-ribose) protein acceptors were identified in the Mr 37,000-120,000 range. It is hypothesized that ADP-ribosylation of specific free mRNP proteins might play a role in the derepression and translation of the silent mRNAs of free mRNP particles. 相似文献
54.
Martin Cambray-Deakin Brian Pearce Christine Morrow Sean Murphy 《Journal of neurochemistry》1988,51(6):1846-1851
Astrocyte-enriched and meningeal cell cultures of the rat cerebral cortex were prepared, and their glycogen content was measured after 10-90 min under control (2.5 mM) concentrations of potassium after prefeeding with 20 mM glucose. No net change in glycogen level was noted in either culture over this period. Cell cultures were then exposed to increased concentrations of potassium (5, 10, and 15 mM), and their glycogen content was measured after 10-90 min. Both types of cell culture showed complex and variable changes in glycogen content. In general, increased potassium concentrations caused astrocyte glycogen stores to be reduced at physiological increases of potassium levels (from 2.5 to 5 mM and above), although a period of resynthesis was evident at all potassium concentrations. Meningeal cell glycogen levels were highly variable and only affected by high (10 and 15 mM) levels of potassium. These results are discussed with respect to the theory that changes in the external potassium concentration caused by neuronal activity might act as a signal controlling astrocyte glycogen stores. 相似文献
55.
Christine L. Truitt Elizabeth A. Weaver William G. Haldenwang 《Molecular & general genetics : MGG》1988,212(1):166-171
Summary The E-37 gene ctc was inactivated by a site-specific insertion into the Bacillus subtilis chromosome. The resulting mutation inhibited sporulation by 95% at elevated temperatures (48° C). If the ctc
- mutation is placed in a strain that carries a mutation in the closely linked but distinct spoVC gene, ctc now affects both growth and sporulation at elevated temperatures. Growth of the ctc
- spoVC285 strain was transiently inhibited when exponentially growing cultures were shifted from 37° C to 48° C. A similar, but less pronounced growth lag, was also seen in a B. subtilis strain carrying only the spoVC-285 mutation. This finding suggests that both the ctc and spoVC products function in vegetatively growing B. subtilis. 相似文献
56.
57.
A serum free medium was developed, that could be used for the large scale propagation of various cell lines in bioreactors. The medium is based on a 1:1 mixture of Iscove's Modified Dulbecco's Medium and Ham's Medium F12, supplemented with transferrin, insulin and a BSA/oleic acid complex. Several myelomas, hybridomas derived from different myelomas and spleen cells, and other lymphoid and non-lymphoid cell lines were cultivated at growth rates comparable to those observed using serum-supplemented media. There was furthermore no reduction in the formation of products such as monoclonal antibodies or recombinant human interleukin-2.Abbreviations Ag8
Mouse myeloma cell line P3-X63-Ag8.653
- BME
Basal Medium Eagle
- BSA
Bovine Serum Albumin
- DMEM
Dulbecco's Modified Eagle's Medium
- EDTA
Ethylenediaminete-traacetic Acid
- e-PC
Phosphatidyl choline from egg yolk
- FCS
Fetal Calf Serum
- FGF
Fibroblast Growth Factor
- GHL
Glycyl-histidyl-lysine
- HDL
High Density Lipoprotein
- HPL
Human Plasma Lipid
- IF
1:1 mixture of IMDM and Ham's F12
- IMDM
Iscove's Modified Dulbecco's medium
- LDL
Low Density Lipoprotein
- NS1
Mouse myeloma cell line NSI-1-Ag4-1
- PBS
Phosphate Buffered Saline
- s-PC
Phosphatidylcholine from soy beans
- s-PE
Phosphatidylethanolamine from soy beans
- s-lecithin
lecithin from soy beans 相似文献
58.
David Mulcahy Christine Wright Lorna Mockus Magdi Yacoub Kim Fox 《BMJ (Clinical research ed.)》1988,296(6625):817-819
Sixty four patients were referred for cardiac transplantation from a single cardiac team at this hospital between October 1984 and December 1986. Of these patients, 33 were referred for urgent transplantation, all of whom required intensive treatment in hospital with intravenous infusions of cardiac drugs, intra-aortic balloon counterpulsation, peritoneal dialysis, ventilation, or any combination of these to sustain life. Of these 33 patients, six died while awaiting transplantation, one was removed from the waiting list for a transplant, and 26 received cardiac transplants. There were five deaths within 24 hours of operation and one death 10 days after the operation. Twenty of those who had surgery had a successful outcome of transplantation, but there was one late death 10 weeks postoperatively and a further death 31 months after surgery. Eighteen patients were alive and well 10 to 33 months (mean 19·4 months) after transplantation, with an overall survival rate after surgery of 69%.Provided that surgery can be performed before renal failure has progressed such that renal transplantation is necessary, the results are excellent (surgical survival 85·5%) and, we believe, justify the expenditure and staffing requirements necessary to treat these terminally ill patients. 相似文献
59.
Andrej Anokhin Ortrud Steinlein Christine Fischer Yiping Mao Peter Vogt Edda Schalt Friedrich Vogel 《Human genetics》1992,90(1-2):99-112
Summary The studied phenotype, the low-voltage electroencephalogram (LVEEG), is characterized by the absence of an alpha rhythm from the resting EEG. In previous studies, evidence was found for a simple autosomal-dominant mode of inheritance of the LVEEG. Such a polymorphism in brain function can be used as a research model for the stepwise elucidation of the molecular mechanism involved in those aspects of neuronal activity that are reflected in the EEG. Linkage with the variable number of tandem repeats (VNTR) marker CMM6 (D20S19) and localization of an LVEEG (EEGV1) gene on 20q have previously been reported, and genetic heterogeneity has been demonstrated. This latter result has been corroborated by studing new marker (MS214). The phenotype of the LVEEG is described here in greater detail. Its main characteristic is the absence of rhythmic alpha activity, especially in occipital leads, whereas other wave forms such as beta or theta waves may be present. Analysis of 17 new families (some of them large), together with 60 previously described nuclear families, supports the genetic hypothesis of an autosomal-dominant mode of inheritance. Problems connected with the analysis of linkage heterogeneity, exclusion mapping, and the study of multipoint linkage are discussed. A possible explanation of the localization of LVEEG in the close vicinity of another gene influencing synchronization of the normal EEG, the gene for benign neonatal epilepsie, is given. 相似文献
60.
S. O'Rahilly P. Patel O. J. Lehmann A. Tybjaerg-Hansen J. Nerup R. C. Turner J. S. Wainscoat 《Human genetics》1992,89(2):207-212
Summary Members of three families with maturity onset diabetes of youth (MODY) and seven with common type 2 diabetes were typed for six DNA markers (H-RAS, INS, HBBC, PTH, CALC1, CAT) on the short arm of chromosome 11. Using conventional pairwise linkage analysis, close linkage in the MODY families was excluded for all six markers. By multipoint analysis and a genetic map of the short arm of chromosome 11, MODY was excluded from a region of at least 35 and up to 60 centiMorgans (cM) on the short arm of chromosome 11. Multipoint analysis in the type 2 families also excludes linkage to the INS, H-RAS region of at least 3 and up to 30 cM. This study using multipoint linkage analysis in non-insulin dependent diabetes provides strong evidence against a role for mutations in or around the insulin gene in the causation of MODY or type 2 diabetes in the families studied. 相似文献