全文获取类型
收费全文 | 5672篇 |
免费 | 374篇 |
国内免费 | 1篇 |
专业分类
6047篇 |
出版年
2023年 | 45篇 |
2022年 | 92篇 |
2021年 | 184篇 |
2020年 | 136篇 |
2019年 | 152篇 |
2018年 | 193篇 |
2017年 | 163篇 |
2016年 | 237篇 |
2015年 | 318篇 |
2014年 | 351篇 |
2013年 | 411篇 |
2012年 | 521篇 |
2011年 | 439篇 |
2010年 | 279篇 |
2009年 | 198篇 |
2008年 | 276篇 |
2007年 | 263篇 |
2006年 | 252篇 |
2005年 | 199篇 |
2004年 | 197篇 |
2003年 | 162篇 |
2002年 | 147篇 |
2001年 | 91篇 |
2000年 | 109篇 |
1999年 | 75篇 |
1998年 | 26篇 |
1997年 | 22篇 |
1996年 | 30篇 |
1995年 | 32篇 |
1994年 | 18篇 |
1993年 | 24篇 |
1992年 | 34篇 |
1991年 | 44篇 |
1990年 | 20篇 |
1989年 | 37篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 27篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1975年 | 11篇 |
1974年 | 11篇 |
1973年 | 12篇 |
1972年 | 9篇 |
1971年 | 8篇 |
排序方式: 共有6047条查询结果,搜索用时 15 毫秒
31.
Pinto LM Pereira R de Paula E de Nucci G Santana MH Donato JL 《Journal of liposome research》2004,14(1-2):51-59
We assessed the effect of local anesthetics (LA) from different families such as esters (benzocaine), linear aminoamides (lidocaine) and cyclic aminoamides (bupivacaine) on the platelet aggregation induced by ADP. Liposomal formulations of the three LA, prepared with egg phosphatidylcholine:cholesterol alpha-tocopherol, were also tested. The three LA were able to inhibit platelet aggregation induced by ADP, in the following order: bupivacaine > lidocaine > benzocaine. After encapsulation into liposomes the inhibitory effect increased for all anesthetics studied, showing that aggregation tests could be used to assess the toxicity of new drug formulations. 相似文献
32.
Despite the growing number of genomes published or currently being sequenced, there is a relative paucity of software for functional classification of newly discovered genes and their assignment to metabolic pathways. Available software for such analyses has a very steep learning curve and requires the installation, configuration, and maintenance of large amounts of complex infrastructure, including complementary software and databases. Many such tools are restricted to one or a few data sources and classification schemes. In this work, we report an automated system for gene annotation and metabolic pathway reconstruction (ASGARD), which was designed to be powerful and generalizable, yet simple for the biologist to install and run on centralized, commonly available computers. It avoids the requirement for complex resources such as relational databases and web servers, as well as the need for administrator access to the operating system. Our methodology contributes to a more rapid investigation of the potential biochemical capabilities of genes and genomes by the biological researcher, and is useful in biochemical as well as comparative and evolutionary studies of pathways and networks. 相似文献
33.
M.F. Arrigoni-Blank A.R. Antoniolli L.C. Caetano D.A. Campos A.F. Blank P.B. Alves 《Phytomedicine》2008,15(5):334-339
Hyptis pectinata L. Poit (Lamiaceae) is known popularly in Brazil as “sambacaita” or “canudinho” and is used in the treatment of inflammations, bacterial infections and ache. The antinociceptive activity of the volatile oils of six genotypes, at doses of 100, 200 and 400 mg/kg body wt., were investigated using abdominal writhe models induced by acetic acid and hot plate tests. The volatile oils of all the genotypes are composed mainly of sesquiterpenoids. All the genotypes showed antinociceptive effects in both models used; the SAM002 genotype showed the major inhibitory effect at dose of 100 mg/kg body wt. These results suggest that the volatile oil of H. pectinata has peripheral (writhe reduction) and central (time delay of thermal reaction) effects. These observations indicate that H. pectinata may be useful as an analgesic drug. 相似文献
34.
This study is an exercise to check the efficiency of the existing reserve system, and to show how systematic conservation
planning—using information available and the complementarity concept—can improve the basis for decisions and minimize costs.
We verified the performance, in number of cells and primate species representation, of the existing Atlantic Forest (Brazil)
reserve network with a quarter-degree resolution grid, with 1,884 cells. We used occurrence data of 20 endemic primate species,
and the maps of 237 existing reserves. Reserve networks were selected to represent primate species first considering no pre-existing
reserves in Atlantic Forest, and then, considering the existing reserve system, taking into account the minimum area for viable
population of the larger species (Northern muriqui Brachyteles hypoxanthus). Reserve selection was carried out using the complementarity concept implemented by a simulated annealing algorithm. Primate
species representation (at least one occurrence in the network) could be achieved with 8% of the existing reserve system (nine
cells in relation to the 120 in the existing reserve system). We found that today’s reserve system represents 89% of endemic
primate species, excluding the species Coimbra Filho’s titi monkey (Callicebus coimbrai) and Marcgraf’s capuchin (Cebus flavius). The networks selected without considering existing reserves contained nine cells. The networks selected considering existing
reserves (120 cells), had two new cells necessary to represent all the primates. This does not mean that a viable alternative
is to start from zero (i.e., nonexistent reserves). Identifying critical supplementary areas using biodiversity information
to fill the gaps and then starting “conservation in practice” in these areas should be priorities. 相似文献
35.
M. L. Gonçalves F. Pinto J. A. Ribeiro 《Nucleosides, nucleotides & nucleic acids》2013,32(5):1161-1163
Abstract The effect of adenosine on 45Ca uptake by rat brain synaptosomes electrically stimulated was studied as function of time of stimulation (10, 30, 120 s). Inhibition of 45Ca uptake was more evident for 120 s. 相似文献
36.
37.
The study was a clinico-mycological approach to find out the various clinical types of dermatophytoses and as well as the species of dermatophytes in Goa. Various socio-demographic and host factors were assessed to determine the predisposing factors for dermatophytoses. A detailed clinical history of the patients was recorded. Samples were collected aseptically in sterile black paper envelopes. The material was subjected to microscopy using potassium hydroxide mount. Culture was done by inoculating the material in Sabouraud’s peptone glucose agar slants. Tinea corporis was found to be the most common clinical presentation (44.2 %). Among the dermatophytes, Trichophyton rubrum predominated (38.2 %), followed by Trichophyton mentagrophytes (27.2 %). Dermatophytoses was more common among the lower and upper lower strata of society. Majority of the patients were in the 21–40 years age group (62 %) with males predominating women in ratio 2.4:1. 相似文献
38.
Marques MA Soares Ade S Pinto OW Barroso PT Pinto DP Ferreira-Filho M Werneck-Barroso E 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,852(1-2):308-316
A rapid and simple method for quantitation of metformin (MET) in human plasma by HPLC-MS/MS was developed and validated. The sample preparation consists of plasma deproteinization using acetonitrile. The mobile phase consisted of water-acetonitrile and formic acid (55/45/0.048, v/v/%) and the run time was 3 min. A pursuit C(18) (100 mm x 2.0 mm i.d., 3 microm) column connected to a guard column MS-pursuit (0.20 mm x 0.20 mm i.d., 5 microm) was used. The range of the calibration curve was from 20 to 5000 ng/mL, the limit of quantitation being 20 ng/mL. The detection was performed on a mass spectrometer (ESI+), using metoprolol as internal standard. The calibration curves have r(2) values of 0.995 (CV=0.24%, n=10). The accuracy and precision were between 90.74 and 106.7% and coefficients of variations (CV) of 1.10 and 4.35%, respectively. The method was applied to determine the pharmacokinetic parameters: C(max) (1667.25 ng/mL) and T(max) (3.89 h). 相似文献
39.
Débora Barbosa Vendramini-Costa Ilton Barros Daltro de Castro Ana Lúcia Tasca Góis Ruiz Cilene Marquissolo Ronaldo Aloise Pilli João Ernesto de Carvalho 《Bioorganic & medicinal chemistry》2010,18(18):6742-6747
In this work the antiproliferative activity of goniothalamin (1), both in racemic and in its enantiomeric pure forms, in a solid tumor experimental model using laboratory animals is described. The antiedematogenic activity displayed by racemic 1 in the carrageenan edema model in mice together with the reduction of Ehrlich solid tumor model suggest a relationship between anticancer and antiinflammatory activities with the antiinflammatory activity favoring the antiproliferative activity itself. 相似文献
40.