全文获取类型
收费全文 | 12753篇 |
免费 | 962篇 |
国内免费 | 5篇 |
出版年
2023年 | 63篇 |
2022年 | 137篇 |
2021年 | 274篇 |
2020年 | 220篇 |
2019年 | 261篇 |
2018年 | 332篇 |
2017年 | 285篇 |
2016年 | 419篇 |
2015年 | 684篇 |
2014年 | 699篇 |
2013年 | 832篇 |
2012年 | 1035篇 |
2011年 | 976篇 |
2010年 | 674篇 |
2009年 | 600篇 |
2008年 | 744篇 |
2007年 | 711篇 |
2006年 | 680篇 |
2005年 | 624篇 |
2004年 | 578篇 |
2003年 | 495篇 |
2002年 | 449篇 |
2001年 | 166篇 |
2000年 | 141篇 |
1999年 | 161篇 |
1998年 | 155篇 |
1997年 | 121篇 |
1996年 | 85篇 |
1995年 | 76篇 |
1994年 | 92篇 |
1993年 | 80篇 |
1992年 | 74篇 |
1991年 | 71篇 |
1990年 | 67篇 |
1989年 | 62篇 |
1988年 | 60篇 |
1987年 | 45篇 |
1986年 | 44篇 |
1985年 | 50篇 |
1984年 | 51篇 |
1983年 | 38篇 |
1982年 | 36篇 |
1981年 | 36篇 |
1980年 | 28篇 |
1979年 | 18篇 |
1978年 | 20篇 |
1976年 | 16篇 |
1975年 | 17篇 |
1974年 | 13篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
H Vaer?y F Nyberg H Franzén L Terenius 《Biochemical and biophysical research communications》1987,148(1):24-30
Enzyme activity capable of converting the glycine-extended substance P precursor, substance P-Gly12, into substance P was purified from human cerebrospinal fluid. The conversion reaction was monitored by radioimmunoassay measurement of substance P formation. The chemical identity of the product was verified by reversed-phase HPLC. The enzyme reaction was stimulated by Cu(II) ion and ascorbic acid and inhibited by the presence of diethyldithiocarbamate. By HPLC molecular sieving, the major enzyme activity appeared as a protein of 26,000 molecular weight. 相似文献
3.
4.
Francisco Gutirrez‐Corchero M. Victoria Arruga Lourdes Sanz Cristina García M. Angeles Hernndez Francisco Campos 《Molecular ecology resources》2002,2(1):75-77
FTA® cards were used for long‐term storage of avian blood samples. Blood DNA was extracted by a simple method and used in PCR for sex identification of adult and nestling Great Grey Shrikes Lanius excubitor. 相似文献
5.
6.
V ronique Cruciani Karen-Marie Heintz Trine Hus y Eivind Hovig David J. Warren Svein-Ole Mikalsen 《Cell communication & adhesion》2004,11(5):155-171
The open reading frames of 17 connexins from Syrian hamster (using tissues) and 16 connexins from the Chinese hamster cell line V79, were fully (Cx30, Cx31, Cx37, Cx43 and Cx45) or partially sequenced. We have also detected, and partially sequenced, seven rat connexins that previously were unavailable. The expression of connexin genes was examined in some hamster organs and cultured hamster cells, and compared with wild-type mouse and the cancer-prone Min mouse. Although the expression patterns were similar for most organs and connexins in hamster and mouse, there were also some prominent differences (Cx29 and 30.3 in testis; Cx31.1 and 32 in eye; Cx46 in brain, kidney and testis; Cx47 in kidney). This suggests that some connexins have species-specific expression profiles. In contrast, there were minimal differences in expression profiles between wild type and Min mice. Species-specific expression profiles should be considered in attempts to make animal models of human connexin-associated diseases. 相似文献
7.
Alicia A. Gil de Pertierra 《Zoologischer Anzeiger》2005,243(4):307-304
The surface of the tegument of the scolex and the immature proglottides of Monticellia belavistensis, M. ventrei, Nomimoscolex chubbi, and N. lopesi is described using scanning electron microscopy. Only blade-like spiniform microtriches and filiform microtriches were observed in the species studied. The types, size and density of microtriches on the apical region surface of the scolex, central cavity surface of suckers, marginal ring surface of suckers, non-adherent surface of suckers, proliferation zone surface, and immature proglottis surface were compared among these species. The distribution pattern of the microtriches was not a reliable feature to discriminate among the genera considered in this study. It varied in each of the species of Monticellia examined, and did not permit to split the heterogeneous genus Nomimoscolex. However, the microthrix pattern can be regarded as an additional diagnostic feature to distinguish among species of proteocephalideans. Further comparative research involving other species of proteocephalid taxa is needed to elucidate the systematic value of the tegumental morphology. 相似文献
8.
9.
We have compared the species richness of medicinal plants and the differential patterns of use amongst settlements in the
Andean communities of Northwest Argentina which have differing levels of isolation. About 259 ethnoespecies, belonging to
74 plant families, were included, representing between 70 and 80% of the total estimate. The results indicate that Coronopus didymus is the most relevant and important species. The method of use of medicinal plants and the ailments treated by rural doctors compared to those of the layperson is different. Native and exotic plants are used differently according to the body system
treated. There are some relationships between internal and external use and body systems and recipes. The greater medicinal
species richness found in the less isolated locations is due to external enriching cultural influences. 相似文献
10.
Francisco E. Fontúrbel 《Mammalian Biology》2010,75(4):294-301
Assessing small mammal diversity is a common procedure, which usually employs widespread standard techniques, for gathering information for a wide range of studies. Traditional methods, however, may be biased against capturing arboreal marsupials, such as Dromiciops gliroides, an endemic marsupial currently considered a rare species in the Patagonian temperate rainforest due to the low abundances reported previously. I tested a new capturing methodology to assess the small mammal diversity of an old-growth forest in Patagonia, based on a randomized and balanced design, which incorporated a combination of different trap types, bait types, and placement heights. The proposed methodology included four trap types (two for live-capturing: wire-mesh and Sherman traps, and two sign-recording traps for tracks and hair), two types of bait (banana and rolled oats), and two trap placements (ground level and 1.5–2.5 m above the ground). Trap type, bait type, and height of placement all had significantly different effects on capturing and detecting rodents or marsupials; environmental variables at the trap location also affected the ability to detect rodents and marsupials. Traditional methods used for sampling small mammals performed well for rodents but are not effective for capturing marsupials and vice versa, showing species-specific sampling protocols. There is no single combination of trap-bait-height capable to assess the entire small mammal community, but the combination of the most effective protocol for rodents and the most effective protocol for marsupials guarantee better results. 相似文献