全文获取类型
收费全文 | 6735篇 |
免费 | 473篇 |
国内免费 | 1篇 |
出版年
2023年 | 26篇 |
2022年 | 56篇 |
2021年 | 137篇 |
2020年 | 92篇 |
2019年 | 104篇 |
2018年 | 155篇 |
2017年 | 137篇 |
2016年 | 225篇 |
2015年 | 314篇 |
2014年 | 338篇 |
2013年 | 454篇 |
2012年 | 526篇 |
2011年 | 521篇 |
2010年 | 323篇 |
2009年 | 289篇 |
2008年 | 435篇 |
2007年 | 411篇 |
2006年 | 398篇 |
2005年 | 347篇 |
2004年 | 311篇 |
2003年 | 269篇 |
2002年 | 263篇 |
2001年 | 69篇 |
2000年 | 49篇 |
1999年 | 58篇 |
1998年 | 92篇 |
1997年 | 41篇 |
1996年 | 60篇 |
1995年 | 67篇 |
1994年 | 39篇 |
1993年 | 54篇 |
1992年 | 44篇 |
1991年 | 41篇 |
1990年 | 32篇 |
1989年 | 25篇 |
1988年 | 23篇 |
1987年 | 38篇 |
1986年 | 27篇 |
1985年 | 30篇 |
1984年 | 26篇 |
1983年 | 26篇 |
1982年 | 21篇 |
1981年 | 24篇 |
1980年 | 24篇 |
1977年 | 11篇 |
1976年 | 13篇 |
1975年 | 18篇 |
1974年 | 11篇 |
1973年 | 13篇 |
1972年 | 13篇 |
排序方式: 共有7209条查询结果,搜索用时 15 毫秒
991.
Autonomic Adaption to Clinical Simulation in Psychology Students: Teaching Applications 总被引:1,自引:0,他引:1
Vicente Javier Clemente-Suárez Ana Isabel Beltrán-Velasco Alberto Bellido-Esteban Pablo Ruisoto-Palomera 《Applied psychophysiology and biofeedback》2018,43(3):239-245
Simulation is used to facilitate new learning in a variety of situations. One application of simulation could be to help therapists gain therapeutic skills prior to seeing clients. This particular study was interested in measuring changes in stress response by looking at subjective and objective measures of distress (as measured by SUDS, HR, and HRV) over three sessions of simulated therapy. 16 second year psychology students participated in three sessions, and had their HR and HRV measured by Polar watches. Over the three sessions, there was a decrease in perceived distress, as measured by SUDS ratings. During and between sessions, there was inconclusive change in physiological parameters. 相似文献
992.
Rafael Castro Buenaventura Brito Vicente Notario 《Cellular and molecular neurobiology》1990,10(2):281-289
1. Previous studies have reported a marked reduction in the [3H]thymidine incorporation in forebrain after administration of a dopamine antagonist such as haloperidol. 2. We have investigated the possibility that the expression levels of genes related to DNA metabolism could be altered by haloperidol treatment. 3. By Northern blot analysis, we have studied the steady-state mRNA levels for genes involved in DNA metabolism, in neonate rat mesencephalon and forebrain, after chronic prenatal blockade of dopamine receptors with haloperidol. 4. We found that the expression levels for DNA polymerases alpha and beta were clearly reduced in forebrain by haloperidol treatment. On the contrary, the expression of DNA polymerase beta was increased in mesencephalon. 5. Our results suggest that dopamine receptors occupancy may be a critical factor in controlling cell proliferation during brain development, through a mechanism(s) involving changes in the expression of DNA polymerases. 相似文献
993.
994.
António Brehm D. James Harris Cíntia Alves José Jesus Fabienne Thomarat Luís Vicente 《Journal of molecular evolution》2002,56(1):46-53
Abstract
We sequenced the complete control region (CR) and adjacent tRNAs, partial 12S rRNA, and cytochrome b (over 3100 bp) from eight individuals of Madeiran wall lizards, Lacerta dugesii, from four distinct island populations. The tRNAs exhibit a high degree of intraspecific polymorphisms compared to other
vertebrates. All CR sequences include a minisatellite that varies in length between populations but is apparently fixed within
them. Variation in minisatellite length appears between populations separated by apparently very short evolutionary time spans.
Many motifs identified in the CR of other vertebrates are not highly conserved, although conserved blocks are identifiable
between the few published reptile CR sequences. Overall there are extensive differences in the internal organization of the
reptile CR compared to the more widely studied mammals and birds. Variability in the CR is lower than in cytochrome b, but higher than in 12S rRNA. Phylogenetic analysis of these sequences produces a well-resolved estimate of relationships
between populations. 相似文献
995.
996.
Sandro L. Fornili Rita Pizzi Davide Rebeccani 《International journal of peptide research and therapeutics》2010,16(4):223-231
We have investigated structural and dynamic properties of the synthetic peptide hlF1-11 (GRRRSVQWCA, i.e., the first 11 N-terminal
amino acids of the human lactoferrin protein) in water, 250 mM NaCl solution, 50% (V/V) water–trifluoroethanol mixture, and
in the membrane mimetic 4:4:1 methanol–chloroform–water mixture. For comparison, we have also performed analogous simulations
for the biologically inactive control peptide featuring Ala substitutions in the 2, 3, 6 and 9 positions of the hlF1-11 sequence.
Statistical analyses of the trajectories indicate that only in the membrane-mimicking medium hlF1-11 adopts preferentially
a conformation suitable to interact effectively with the membrane. In this conformation the peptide cationic region is rather
flexible and elongated, while the C-terminal hydrophobic moiety appears as a more rigid hairpin-shaped loop approximately
perpendicular to the cationic region. No such conformation is statistically relevant for the control peptide. 相似文献
997.
Pedro J. Alcolea Ana Alonso Francisco García-Tabares Alfredo Tora?o Vicente Larraga 《PloS one》2014,9(12)
The life cycle of the trypanosomatid Crithidia fasciculata is monogenetic, as the unique hosts of these parasites are different species of culicids. The comparison of these non-pathogenic microorganisms evolutionary close to other species of trypanosomatids that develop digenetic life cycles and cause chronic severe sickness to millions of people worldwide is of outstanding interest. A ground-breaking analysis of differential protein abundance in Crithidia fasciculata is reported herein. The comparison of the outcome with previous gene expression profiling studies developed in the related human pathogens of the genus Leishmania has revealed substantial differences between the motile stages of these closely related organisms in abundance of proteins involved in catabolism, redox homeostasis, intracellular signalling, and gene expression regulation. As L. major and L. infantum agglutinate with peanut lectin and non-agglutinating parasites are more infective, the agglutination properties were evaluated in C. fasciculata. The result is that choanomastigotes are able to agglutinate with peanut lectin and a non-agglutinating subpopulation can be also isolated. As a difference with L. infantum, the non-agglutinating subpopulation over-expresses the whole machinery for maintenance of redox homeostasis and the translation factors eIF5a, EF1α and EF2, what suggests a relationship between the lack of agglutination and a differentiation process. 相似文献
998.
999.
Pere Fullana i Palmer Rita Puig Alba Bala Grau Baquero Jordi Riba Marco Raugei 《Journal of Industrial Ecology》2011,15(3):458-475
Life cycle assessment (LCA) is a widely accepted methodology to support decision‐making processes in which one compares alternatives, and that helps prevent shifting of environmental burdens along the value chain or among impact categories. According to regulation in the European Union (EU), the movement of waste needs to be reduced and, if unavoidable, the environmental gain from a specific waste treatment option requiring transport must be larger than the losses arising from transport. The EU explicitly recommends the use of LCA or life cycle thinking for the formulation of new waste management plans. In the last two revisions of the Industrial Waste Management Programme of Catalonia (PROGRIC), the use of a life cycle thinking approach to waste policy was mandated. In this article we explain the process developed to arrive at practical life cycle management (LCM) from what started as an LCA project. LCM principles we have labeled the “3/3” principle or the “good enough is best” principle were found to be essential to obtain simplified models that are easy to understand for legislators and industries, useful in waste management regulation, and, ultimately, feasible. In this article, we present the four models of options for the management of waste solvent to be addressed under Catalan industrial waste management regulation. All involved actors concluded that the models are sufficiently robust, are easy to apply, and accomplish the aim of limiting the transport of waste outside Catalonia, according to the principles of proximity and sufficiency. 相似文献
1000.