全文获取类型
收费全文 | 5015篇 |
免费 | 484篇 |
国内免费 | 1篇 |
出版年
2023年 | 21篇 |
2022年 | 16篇 |
2021年 | 91篇 |
2020年 | 62篇 |
2019年 | 70篇 |
2018年 | 73篇 |
2017年 | 72篇 |
2016年 | 140篇 |
2015年 | 228篇 |
2014年 | 250篇 |
2013年 | 332篇 |
2012年 | 446篇 |
2011年 | 387篇 |
2010年 | 270篇 |
2009年 | 256篇 |
2008年 | 321篇 |
2007年 | 335篇 |
2006年 | 323篇 |
2005年 | 307篇 |
2004年 | 287篇 |
2003年 | 274篇 |
2002年 | 293篇 |
2001年 | 63篇 |
2000年 | 39篇 |
1999年 | 60篇 |
1998年 | 76篇 |
1997年 | 46篇 |
1996年 | 33篇 |
1995年 | 43篇 |
1994年 | 33篇 |
1993年 | 32篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 21篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有5500条查询结果,搜索用时 15 毫秒
61.
62.
C D Bridges G I Liou R A Alvarez R A Landers A M Landry S L Fong 《The Journal of experimental zoology》1986,239(3):335-346
Immunoblots of interphotoreceptor matrix preparations from 20 species belonging to six vertebrate classes were probed with antibodies against bovine interstitial retinol-binding protein (b-IRBP). Each preparation displayed an immunoreactive protein band. In the Osteichthyes, the apparent Mr of this band was 67,600 +/- 2,700 (mean +/- SD, n = 8). In two of the Osteichthyes, the band was resolved into a closely spaced doublet. Including previously published data for five mammals and one amphibian, species from the other classes (Chondrichthyes, one species; Amphibia, four species; Reptilia, one species; Aves, one species; Mammalia, nine species) had IRBPs with Mr that averaged 2.0 times that of the Osteichthyes, namely 134,200 +/- 8,600 (mean +/- SD, n = 17). Frog IRBP was very similar to mammalian IRBP in terms of its immunohistochemical distribution (determined with rabbit anti-frog IRBP antibodies), its molecular weight (sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel-filtration chromatography), retinol- and concanavalin A-binding ability, and because it was synthesized and secreted in vitro by the isolated retina but not by the pigmented layers of eye. Goldfish IRBP apparently binds exogenous (3H)-retinol but does not bind concanavalin A and has about half the Mr of frog IRBP. The occurrence of IRBP-like proteins cross-reacting with anti b-IRBP antibodies in the interphotoreceptor matrix of all six major vertebrate classes is consistent with the hypothesis that IRBP is an important element in the vertebrate visual cycle. 相似文献
63.
C C Landry R W Topham 《Comparative biochemistry and physiology. B, Comparative biochemistry》1990,97(4):831-836
The presence of an iron-binding protein in the hemolymph of the blue crab (Callinectes sapidus) was detected by gel filtration of 59Fe-labeled hemolymph. The iron-binding protein was purified to homogeneity by ion exchange chromatography. 2. This protein has a mol. wt of 155,000 and consists of a single polypeptide chain with an isoelectric point of 5.0. 3. Analysis of the iron-loaded protein indicates that it has a high affinity for iron and the capacity to bind approximately 10 atoms iron/molecule protein. 4. The isolation of a specific iron-binding protein from the blue crab (Callinectes sapidus) provides additional support for the proposal that such proteins are an ancient evolutionary development not necessarily linked to the appearance of iron proteins (hemoglobin and hemerythrin) as a means for oxygen transport. 相似文献
64.
Persistence of conidia of the entomopathogenic fungus Paecilomyces fumosoroseus exposed to artificial and solar radiation at a constant temperature was studied by monitoring the ability to germinate and to form colonies (colony - forming units , CFUs) . The photic effect of radiation on each of these variables was modelled by a decreasing function of UVB irradiation ( in J m 2) . Germination ability was represented by a logistic function and viability (log CFU) by an infinitely decreasing function . Experiments carried out under artificial conditions , at three different UVB irradiances ( from 0 . 3 to 1 . 6 W m 2) , similar to those observed in nature , confirmed the adequacy of the predictor variable and of the functions chosen for describing these data . The proposed models appeared to be irradiance independent . Under solar radiation , the models were able to describe data collected on three different summer days in France (48 o 51 N , 2 o 06 E) . However , it took a greater amount of solar UVB radiation to produce the same effect as that achieved indoors . This could be explained by differences in radiation spectra . For each model , one set of parameters was sufficient for representing all three sets of data: this constitutes an initial validation of the models proposed . 相似文献
65.
A checklist of identified oribatid mite taxa from riverine freshwater environments from six islands in Polynesia (New Caledonia, Tahiti, Moorea, Rurutu, Tubuai, Raiatea) is presented; 18 species, 16 genera and eight families were recorded. Trhypochthoniellus longisetus (Berlese, 1904) and Trimalaconothrus albulus Hammer, 1972 prevailed on distribution. Fortuynia smiti
sp. n. (Fortuyniidae) is described from New Caledonia. The new speciesis morphologically most similar to Fortuynia marina Hammen, 1960 from New Guinea, but it differs from the latter by the longer notogastral setae dm, lm, c2, p1, epimeral setae 3b and adanal setae ad1 and the presence of prodorsal lateral ridges. 相似文献
66.
Michael Landry 《CMAJ》1977,116(12):1392-1394
Although odontogenic keratocysts are benign they are often locally destructive and tend to recur after conservative surgical treatment. They must therefore be distinguished from other cysts of the jaw. Keratocysts possess outpouchings and microscopic daughter cysts from which recurrences may arise. Histologic examination is essential for diagnosis since the appearances on roentgenograms and at operation usually do not reveal the true nature of the lesion. Since many nondental surgeons and pathologists are unaware of odontogenic keratocysts a case is presented in which surgical treatment was originally conservative and finally relatively radical. 相似文献
67.
68.
69.
Martin Lange Laure Guillou Daniel Vaulot Nathalie Simon Rudolf I. Amann Wolfgang Ludwig Linda K. Medlin 《Journal of phycology》1996,32(5):858-868
Target regions specific for the class Prymnesiophyceae and the genus Phaeocystis (Har.) Lag. were identified from 18S ribosomal RNA coding regions, and two complementary probes were designed (PRYMN01 and PHAEO01). Detection of whole cells hybridized with these probes labeled with fluorescein isothiocyanate was difficult using epifluorescence microscopy because autofluorescence of the chlorophylls seriously interfered with the fluorescence of the probes. In contrast, flow cytometry proved very useful to detect and quantify the fluorescence of the hybridized cells. Hybridization conditions were optimized, especially with respect to formamide concentration. Both probes were tested on a large array of both target and nontarget strains. Positive and negative controls were also analyzed. Specificity was tested by adding a competing nonlabeled probe. Whereas probe PHAEO01 seems to have good specificity, probe PRYMN01 appeared less specific and must be used with stringent positive and negative controls. 相似文献
70.
Kai Bao Xiaofei Li Tetsuhiro Kajikawa Abe Toshiharu Nathalie Selevsek Jonas Grossmann George Hajishengallis Nagihan Bostanci 《Proteomics》2020,20(3-4)
Understanding the progression of periodontal tissue destruction is at the forefront of periodontal research. The authors aimed to capture the dynamics of gingival tissue proteome during the initiation and progression of experimental (ligature‐induced) periodontitis in mice. Pressure cycling technology (PCT), a recently developed platform that uses ultra‐high pressure to disrupt tissues, is utilized to achieve efficient and reproducible protein extraction from ultra‐small amounts of gingival tissues in combination with liquid chromatography‐tandem mass spectrometry (MS). The MS data are processed using Progenesis QI and the regulated proteins are subjected to METACORE, STRING, and WebGestalt for functional enrichment analysis. A total of 1614 proteins with ≥2 peptides are quantified with an estimated protein false discovery rate of 0.06%. Unsupervised clustering analysis shows that the gingival tissue protein abundance is mainly dependent on the periodontitis progression stage. Gene ontology enrichment analysis reveals an overrepresentation in innate immune regulation (e.g., neutrophil‐mediated immunity and antimicrobial peptides), signal transduction (e.g., integrin signaling), and homeostasis processes (e.g., platelet activation and aggregation). In conclusion, a PCT‐assisted label‐free quantitative proteomics workflow that allowed cataloging the deepest gingival tissue proteome on a rapid timescale and provided novel mechanistic insights into host perturbation during periodontitis progression is applied. 相似文献