全文获取类型
收费全文 | 8290篇 |
免费 | 607篇 |
国内免费 | 6篇 |
出版年
2023年 | 42篇 |
2022年 | 75篇 |
2021年 | 156篇 |
2020年 | 99篇 |
2019年 | 134篇 |
2018年 | 161篇 |
2017年 | 124篇 |
2016年 | 246篇 |
2015年 | 374篇 |
2014年 | 466篇 |
2013年 | 491篇 |
2012年 | 662篇 |
2011年 | 562篇 |
2010年 | 392篇 |
2009年 | 330篇 |
2008年 | 414篇 |
2007年 | 438篇 |
2006年 | 345篇 |
2005年 | 387篇 |
2004年 | 359篇 |
2003年 | 313篇 |
2002年 | 294篇 |
2001年 | 108篇 |
2000年 | 96篇 |
1999年 | 99篇 |
1998年 | 97篇 |
1997年 | 78篇 |
1996年 | 63篇 |
1995年 | 67篇 |
1994年 | 52篇 |
1993年 | 52篇 |
1992年 | 68篇 |
1991年 | 55篇 |
1990年 | 43篇 |
1989年 | 49篇 |
1988年 | 42篇 |
1987年 | 43篇 |
1986年 | 44篇 |
1985年 | 45篇 |
1984年 | 52篇 |
1982年 | 41篇 |
1979年 | 42篇 |
1978年 | 35篇 |
1977年 | 41篇 |
1976年 | 32篇 |
1975年 | 40篇 |
1974年 | 30篇 |
1973年 | 35篇 |
1971年 | 30篇 |
1970年 | 32篇 |
排序方式: 共有8903条查询结果,搜索用时 234 毫秒
31.
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
32.
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
33.
Oskar organizes the germ plasm and directs localization of the posterior determinant nanos 总被引:33,自引:0,他引:33
Oskar is one of seven Drosophila maternal-effect genes that are necessary for germline and abdomen formation. We have cloned oskar and show that oskar RNA is localized to the posterior pole of the oocyte when germ plasm forms. This polar distribution of oskar RNA is established during oogenesis in three phases: accumulation in the oocyte, transport toward the posterior, and finally maintenance at the posterior pole of the oocyte. The colocalization of oskar and nanos in wild-type and bicaudal embryos suggests that oskar directs localization of the posterior determinant nanos. We propose that the pole plasm is assembled stepwise and that continued interaction among its components is required for germ cell determination. 相似文献
34.
35.
Karl Hård Albert Mekking Johannis P. Kamerling Georges A. A. Dacremont Johannes F. G. Vliegenthart 《Glycoconjugate journal》1991,8(1):17-28
Five brain-derived and 17 urinary oligomannose-type oligosaccharides were isolated by ion-exchange chromatography on Mono Q or Dowex, followed by HPLC on Lichrosorb-NH2 from a Persian cat suffering from -mannosidosis. The structures ofthe carbohydrate chains were determined by 500- or 600-MHz1H-NMR spectroscopy. Different oligosaccharide patterns were found in brain and urine. 99% of the urinary oligosaccharides possess an (1-6)-linked mannose residue attached to -mannose, whereas only 5% of the brain-derived oligosaccharides contain such a residue. Furthermore, of the urinary carbohydrate chains 71% end with Man1-4GlcNAc1-4GlcNAc and 29% end with Man1-4GlcNAc, whereas the corresponding amounts are 23% and 77%, respectively, for the brain-derived oligosaccharides.Abbreviations MLEV-17
composite pulse devised by M. Levitt
- HOHAHA
homonuclear Hartman-Hahn spectroscopy
- TPPI
time-proportional phase incrementation
- 2D
two dimensional
- GlcNAc
N-acetylglucosamine
- Man
mannose
- Fuc
fucose 相似文献
36.
37.
Influences of the salt concentration on the fatty acid composition of Ectothiorhodospira species and other phototrophic purple bacteria have been analysed. Major fatty acids in bacteria of the genera Rhodobacter, Rhodopseudomonas, Chromatium, and Ectothiorhodospira were straight chain saturated and monounsaturated C-16 and C-18 fatty acids. Salt-dependent responses of all investigated bacteria revealed relations to their salt optima. Minimum values of C-16 and saturated fatty acids and maximum values of C-18 and unsaturated fatty acids were found at or close to the salt optima. Responses of Ectothiorhodospira mobilis upon changes in salinity were nearly identical, whether cells were grown in batch culture or in continuous culture with identical dilution rates at all salt concentrations. With increasing temperature, the fatty acid composition of Ectothiorhodospira mobilis and Ectothiorhodospira halophila strains showed decreasing portions of C-18 and of unsaturated fatty acids, while the contents of C-16 and saturated fatty acids increased. The results are discussed with respect to bilayer stabilisation and membrane fluidity.Abbreviations PC
phosphatidylcholine
- PG
phosphatidylglycerol
- CL
cardiolipin
- PE
phosphatidylethanolamine 相似文献
38.
Chromosome abnormalities found among 34910 newborn children: results from a 13-year incidence study in Århus,Denmark 总被引:2,自引:2,他引:0
Summary As part of a larger prospective study of the influence of environmental factors on pregnancy, birth and the fetus, chromosome examinations have been made in 34910 newborn children in Århus over a 13-year period. Klinefelter's syndrome was found in 1 per 576 boys, XYY in 1 per 851 boys, triple-X in 1 per 947 girls and Turner's syndrome in 1 per 1893 girls. Other sex chromosome aberrations were found in 1 per 11637 children. The total incidence of sex chromosome abnormalities was 1 per 426 children or 2.34 per 1000. The most frequent autosomal abnormalities were that of Down's syndrome with 1 per 592 children, and reciprocal translocations with 1 per 712 children. The total incidence of autosomal abnormalities was 1 per 164 children. Chromosome abnormalities were found in 276 liveborn children and in 19 fetuses, who were aborted after prenatal chromosome examination. The combined incidence of sex chromosomal and autosomal abnormalities was 1 per 118 children or 8.45 per 1000 children. 相似文献
39.
Johannes M. Zanker Martin Egelhaaf Anne-Kathrin Warzecha 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(2):127-134
Summary In tethered flying houseflies (Musca domestica), the yaw torque produced by the wings is accompanied by postural changes of the abdomen and hindlegs. In free flight, these body movements would jointly lead to turning manoeuvres of the animal. By recording the yaw torque together with the lateral deflections of either the abdomen or the hindlegs, it is shown that these motor output systems act in a highly synergistic way during two types of visual orientation behavior, compensatory optomotor turning reactions and orientation turns elicited by moving objects. This high degree of coordination is particularly conspicuous for the pathway activated by moving objects. Here, orientation responses either may be induced or may fail to be generated always simultaneously in all three motor output systems. This suggests that the pathway mediating orientation turns towards objects is gated before it segregates into the respective motor control systems of the wings, the abdomen and the hindlegs. 相似文献
40.
C N Parris C F Arlett A R Lehmann M H Green J R Masters 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1988,53(4):599-608
Gamma radiation sensitivities of continuous cell lines from nine human tumours were measured, comparing four derived from transitional cell carcinomas of the bladder with five from non-seminomatous germ cell tumours of the testis. The testicular cells were significantly more radiosensitive than the bladder cells, corresponding to the response to therapy of these tumour types in patients. These observations indicate that radiosensitivity is retained in vitro and is an inherent property of the testicular tumour cells. These gamma radiation sensitivities were compared with those of SV40-transformed fibroblasts derived from a normal individual and one with the heritable disease, ataxia-telangiectasia (A-T). The bladder cells had gamma radiation sensitivities similar to that of the SV40-transformed normal line. The testicular cells were hypersensitive to gamma radiation, although not as sensitive as the SV40-transformed A-T line. A-T cells, unlike those derived from normal individuals, continue to synthesize DNA at a normal rate following radiation exposure, prompting a comparison of the kinetics of DNA synthesis in three bladder and three testicular tumour cell lines. One of the bladder and two testicular lines showed a reduced inhibition when compared to the other tumour cell lines and the SV40-transformed normal line. Thus there was no clear association between DNA synthesis inhibition and radiosensitivity. 相似文献