全文获取类型
收费全文 | 2942篇 |
免费 | 238篇 |
国内免费 | 1篇 |
出版年
2022年 | 14篇 |
2021年 | 48篇 |
2020年 | 14篇 |
2019年 | 21篇 |
2018年 | 24篇 |
2017年 | 26篇 |
2016年 | 60篇 |
2015年 | 82篇 |
2014年 | 119篇 |
2013年 | 145篇 |
2012年 | 171篇 |
2011年 | 152篇 |
2010年 | 111篇 |
2009年 | 111篇 |
2008年 | 152篇 |
2007年 | 153篇 |
2006年 | 147篇 |
2005年 | 134篇 |
2004年 | 113篇 |
2003年 | 146篇 |
2002年 | 112篇 |
2001年 | 64篇 |
2000年 | 63篇 |
1999年 | 57篇 |
1998年 | 57篇 |
1997年 | 36篇 |
1996年 | 43篇 |
1995年 | 43篇 |
1994年 | 34篇 |
1993年 | 36篇 |
1992年 | 50篇 |
1991年 | 47篇 |
1990年 | 46篇 |
1989年 | 46篇 |
1988年 | 46篇 |
1987年 | 38篇 |
1986年 | 25篇 |
1985年 | 43篇 |
1984年 | 26篇 |
1983年 | 19篇 |
1982年 | 33篇 |
1981年 | 18篇 |
1980年 | 23篇 |
1979年 | 38篇 |
1978年 | 14篇 |
1977年 | 23篇 |
1976年 | 16篇 |
1975年 | 16篇 |
1974年 | 17篇 |
1973年 | 19篇 |
排序方式: 共有3181条查询结果,搜索用时 31 毫秒
1.
Sandrine Poncet Armelle Delecluse Guido Anello ré Klier Georges Rapoport 《FEMS microbiology letters》1994,117(1):91-95
Abstract The genes encoding the CryIVB and CryIVD crystal polypeptides of B. thuringiensis subsp. israelensis were cloned indepently on a stable shuttle vector, and transfered into B. sphaericus 2297. Recombinant cells expressed the B. thuringiensis toxins during sporulation and were shown to be toxic to Aedes aegypti fourth instar larvae, whereas the parental strain was not. 相似文献
2.
Pierre Beuchet Laïla El kihel Michel Dherbomez Georges Charles Yves Letourneux 《Bioorganic & medicinal chemistry letters》1998,8(24):931
Δ7-5-Desaturase catalyses one of the last steps in ergosterol biosynthesis in fungi. Moreover Δ5-unsaturation is necessary for the sparking function. Synthesis of three pairs of C-6 epimeric cholestanol derivatives are described as potential growth inhibitors. Preliminary results suggest that 6β-aminocholestanol is a potent antifungal agent. 相似文献
3.
Georges Lantéri-Laura 《PSN》2003,1(3):39-47
The author describes the history of the concept of depression in modern psychiatry from the end of the Age of Enlightenment until today in three parts. In the first period (1793–1854), the opposition of general delusion (mania) and partial delusion (melancholia) prevails, without the problem of changes of the affective state being an issue. Only with the work of J. Guislain, and later of W. Griesinger, does the concept of mood disorders become a categorical form in mental pathology with the idea of psychological pain. The second period (1854–1926) is distinguished firstly by the works of J.P. Falret on circular insanity, and then those of V. Magnan, J. Ségnan, J. Séglas et Ph. Chaslin in France and E. Kraepelin in Germany. This period is characterized by the classical construction of periodic manicdepressive psychosis and takes into account the opposition of mania and melancholia. In the third period (1926–1977), the influences of phenomenology, psychoanalysis and structuralism predominate. Gradually melancholia loses its place at the core of this field, in favour of the concept of depression and this change now characterizes contemporary psychiatry. 相似文献
4.
Nimra Khan Dylan Pelletier Thomas S. McAlear Nathalie Croteau Simon Veyron Andrew N. Bayne Corbin Black Muneyoshi Ichikawa Ahmad Abdelzaher Zaki Khalifa Sami Chaaban Igor Kurinov Gary Brouhard Susanne Bechstedt Khanh Huy Bui Jean-François Trempe 《Structure (London, England : 1993)》2021,29(6):572-586.e6
- Download : Download high-res image (220KB)
- Download : Download full-size image
5.
6.
We isolated a Zea mays cDNA encoding the 40S subunit cytoplasmic ribosomal protein S11. The nucleotide sequence was determined and the derived amino acid sequence compared to the corresponding Arabidopsis thaliana protein showing an homology of 90%. This ribosomal protein is encoded by a small multigene family of at least two members. The mRNA steady-state level is about one order of magnitude higher in rapidly growing parts of the plant such as the roots and shoots of seedlings compared to fully expanded leaf tissue. 相似文献
7.
Adriana Calderaro Giovanna Piccolo Chiara Gorrini Sara Montecchini Sabina Rossi Maria Cristina Medici Carlo Chezzi Georges Snounou 《PloS one》2012,7(10)
It has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasites: P. ovale curtisi and P. ovale wallikeri. We have extended and optimized a Real-time PCR assay targeting the parasite’s small subunit ribosomal RNA (ssrRNA) gene to detect both these species. When the assay was applied to 31 archival blood samples from patients diagnosed with P. ovale, it was found that the infection in 20 was due to P. ovale curtisi and in the remaining 11 to P. ovale wallikeri. Thus, this assay provides a useful tool that can be applied to epidemiological investigations of the two newly recognized distinct P. ovale species, that might reveal if these species also differ in their clinical manifestation, drugs susceptibility and relapse periodicity. The results presented confirm that P. ovale wallikeri is not confined to Southeast Asia, since the majority of the patients analyzed in this study had acquired their P. ovale infection in African countries, mostly situated in West Africa. 相似文献
8.
9.
The Spanish ``Asturiana' cattle breed is characterized by the segregation of a genetically determined muscular hypertrophy
referred to as double-muscling or ``culones'. We demonstrate by linkage analysis that this muscular hypertrophy involves
the mh locus previously shown to cause double-muscling in the Belgian Blue cattle breed, pointing towards locus homogeneity of this
trait across both breeds. Moreover, using a twopoint and multipoint maximum likelihood approach, we show that flanking microsatellite
markers are in linkage disequilibrium with the mh locus in both breeds albeit with different alleles. Finally, we discuss how allelic homogeneity across breeds might be exploited
to achieve efficient genetic fine-mapping of the mh locus.
Received: 13 September 1996 / Accepted: 20 January 1997 相似文献
10.
O. Van Reeth S. Goldman S. Schiffmann A. Verstappen G. Pelletier H. Vaudry J. J. Vanderhaeghen 《Peptides》1987,8(6):1107-1117
Immunocytochemical techniques have been used to study neuropeptide Y (NPY) distribution in the human visual cortex (Brodman's areas 17, 18 and 19) NYP cell bodies belong mostly to inhibitory (multipolar and bitufted) but also to excitatory (bipolar and some pyramidal) neuronal types. Their distribution is similar in the three cortical areas studied: 20 to 40% of the NPY perikarya are located in the cortical gray matter, mostly in the deep layers, while the remaining 60 to 80% are located in the underlying white matter. Immunoreactive NPY processes form a rich network of intersecting fibers throughout the entire visual cortex. A superficial plexus (layers I and II) and a deep plexus (deep layer V and layer VI) of NPY fibers are present in areas 17, 18 and 19. In area 17, an additional well developed plexus is present in layers IVb and IVc. These plexuses receive branches from long parallel fibers arising from deep cortical layers or underlying white matter and terminating in superficial layers. Local or extrinsic NPY terminals wind around vessels in the cortex as well as in the white matter, and either penetrate them or form clusters of club endings on their walls. Our results suggest a role for NPY in human visual circuitry and in cortical blood flow regulation. 相似文献