全文获取类型
收费全文 | 7160篇 |
免费 | 782篇 |
国内免费 | 3篇 |
出版年
2024年 | 11篇 |
2023年 | 30篇 |
2022年 | 112篇 |
2021年 | 180篇 |
2020年 | 83篇 |
2019年 | 129篇 |
2018年 | 158篇 |
2017年 | 137篇 |
2016年 | 212篇 |
2015年 | 374篇 |
2014年 | 391篇 |
2013年 | 474篇 |
2012年 | 642篇 |
2011年 | 618篇 |
2010年 | 405篇 |
2009年 | 400篇 |
2008年 | 469篇 |
2007年 | 499篇 |
2006年 | 439篇 |
2005年 | 398篇 |
2004年 | 408篇 |
2003年 | 329篇 |
2002年 | 291篇 |
2001年 | 61篇 |
2000年 | 45篇 |
1999年 | 64篇 |
1998年 | 76篇 |
1997年 | 47篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 23篇 |
1991年 | 15篇 |
1990年 | 20篇 |
1989年 | 26篇 |
1988年 | 22篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 16篇 |
1983年 | 21篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1974年 | 16篇 |
1971年 | 7篇 |
排序方式: 共有7945条查询结果,搜索用时 484 毫秒
31.
32.
Fingerprint protein patterns were produced by two-dimensional polyacrylamide electrophoresis on lysed cells of a Vibrio sp., Ant-300, which were prepared from growing and starved cultures. The cells were labeled with [35S]methionine during growth and subsequently starved for up to 30 days. Samples were taken at selected time points representing stages in the starvation-survival process. Unlabeled starved cells were allowed to recover in the presence of [35S]methionine to determine protein changes associated with the recovery from starvation. All growth conditions produced similar protein fingerprints; however, some protein spots disappeared, whereas others were seen only during starvation. 相似文献
33.
34.
35.
Recovery of diaphragm function after laparotomy and chronic sonomicrometer implantation 总被引:4,自引:0,他引:4
Easton P. A.; Fitting J. W.; Arnoux R.; Guerraty A.; Grassino A. E. 《Journal of applied physiology》1989,66(2):613-621
If sonomicrometry transducers could be implanted permanently into the diaphragm, direct measurements of costal and crural length and shortening could be made during recovery from the laparotomy and then indefinitely in an awake, non-anesthetized mammal. We report results from six canines in which we successfully implanted transducers onto the left hemidiaphragm through a midline laparotomy and measured segmental shortening and ventilation at intervals through 22 days of postoperative recovery. After laparotomy, breathing pattern, including tidal volume, respiratory rate and mean inspiratory flow, stabilized by the 4th postoperative day (POD). Tidal shortening of costal and crural segments increased from 1.82 and 1.45% of end-expiratory length (%LFRC) on the 2nd POD to 5.32 and 8.56% LFRC, respectively, after a mean of 22 POD. Segmental shortening did not stabilize until 10 POD, and the recovery process displayed a sequence of segmental motions: lengthening, biphasic inspiratory lengthening-shortening, and increasing simple shortening. Three weeks after implantation, costal and crural segments were stable and shortening 5.32 and 8.56% LFRC, respectively, and capable of shortening 49% LFRC with maximal phrenic stimulation. In a pair of recovered animals, the initial postoperative dysfunction did not recur after a subsequent, simple laparotomy. At postmortem examination, the chronically implanted sonomicrometer transducers were found to have evoked only a thin fibrotic capsule within the diaphragm. 相似文献
36.
37.
Wayne W. Grody Deborah Klein Amy E. Dodson Rita M. Kern Paul B. Wissmann Barbara K. Goodman Patrick Bassand Bert Marescau Soo-Sang Kang James V. Leonard Stephen D. Cederbaum 《American journal of human genetics》1992,50(6):1281-1290
We have explored the molecular pathology in 28 individuals homozygous or heterozygous for liver arginase deficiency (hyperargininemia) by a combination of Southern analysis, western blotting, DNA sequencing, and PCR. This cohort represents the majority of arginase-deficient individuals worldwide. Only 2 of 15 homozygous patients on whom red blood cells were available had antigenically cross-reacting material as ascertained by western blot analysis using anti-liver arginase antibody. Southern blots of patient genomic DNAs, cut with a variety of restriction enzymes and probed with a near-full-length (1,450-bp) human liver arginase cDNA clone, detected no gross gene deletions. Loss of a TaqI cleavage site was identified in three individuals: in a homozygous state in a Saudi Arabian patient at one site, at a different site in homozygosity in a German patient, and in heterozygosity in a patient from Australia. The changes in the latter two were localized to exon 8, through amplification of this region by PCR and electrophoretic analysis of the amplified fragment after treatment with TaqI; the precise base changes (Arg291X and Thr290Ser) were confirmed by sequencing. It is interesting that the latter nucleotide variant (Thr290Ser) was found to lie adjacent to the TaqI site rather than within it, though whether such a conservative amino acid substitution represents a true pathologic mutation remains to be determined. We conclude that arginase deficiency, though rare, is a heterogeneous disorder at the genotypic level, generally encompassing a variety of point mutations rather than substantial structural gene deletions. 相似文献
38.
39.
R.Lucille Roberts Amy Zullo Eric A. Gustafson C.Sue Carter 《Hormones and behavior》1996,30(4):576-582
This experiment was designed to examine the hypothesis that perinatal manipulation of gonadal or adrenal steroids can alter the subsequent expression of juvenile parental (alloparenting) and affiliative behavior in prairie voles (Microtus ochrogaster). Corticosterone (PRECORT), testosterone (PRE-TP), or oil injections (PRESES) were given on Prenatal Days 12–20 or on Postnatal Days 1–6 (CORT6, TP6, or SES6, respectively). Alloparenting was reduced significantly in females in the CORT6 group and in males in the TP6 group. Sibling affiliative preferences were increased significantly in PRE-TP females and stranger preferences were increased in TP6 and CORT6 females. The results suggest timing is a critical factor determining whether hormones have a facilitative or inhibitory effect on alloparental and affiliative behavior in prairie voles. In this species, corticosterone and testosterone have similar organizational effects on affiliative behavior in females. Alloparental behavior is inhibited by postnatal corticosterone administration in females and by postnatal testosterone administration in males, whereas prenatal steroid administration had no significant effect on alloparenting in either gender. 相似文献
40.
Computational sequence analysis of matrix metalloproteinases 总被引:12,自引:0,他引:12
Matrix metalloproteinases (MMP) play a cardinal role in the breakdown of extracellular matrix involved in a variety of biological and pathological processes. Research on MMPs has classified and characterized these enzymes according to their matrix substrate specificity, gene and protein domain structure, and regulation of activity and expression. However, the discovery of new MMPs has introduced a need for a more comprehensive and systematic method of classification and quantitative comparison of known and newly discovered members. This study compiles a sequence alignment, constructs a dendrogram, and calculates physical data and homology percentage assignments in order to obtain further insight into MMP structure-function relationships. Thorough analysis of MMP primary sequence domains, physical data patterns, and statistical analysis of sequence homology yields higher resolution in the similarities and differences that group MMP members. 相似文献