全文获取类型
收费全文 | 6719篇 |
免费 | 581篇 |
国内免费 | 6篇 |
专业分类
7306篇 |
出版年
2023年 | 19篇 |
2022年 | 102篇 |
2021年 | 165篇 |
2020年 | 85篇 |
2019年 | 95篇 |
2018年 | 161篇 |
2017年 | 125篇 |
2016年 | 216篇 |
2015年 | 363篇 |
2014年 | 409篇 |
2013年 | 468篇 |
2012年 | 591篇 |
2011年 | 526篇 |
2010年 | 318篇 |
2009年 | 250篇 |
2008年 | 402篇 |
2007年 | 386篇 |
2006年 | 315篇 |
2005年 | 316篇 |
2004年 | 306篇 |
2003年 | 213篇 |
2002年 | 223篇 |
2001年 | 208篇 |
2000年 | 144篇 |
1999年 | 113篇 |
1998年 | 52篇 |
1997年 | 35篇 |
1996年 | 45篇 |
1995年 | 34篇 |
1994年 | 30篇 |
1993年 | 23篇 |
1992年 | 56篇 |
1991年 | 36篇 |
1990年 | 39篇 |
1989年 | 34篇 |
1988年 | 31篇 |
1987年 | 37篇 |
1986年 | 25篇 |
1985年 | 24篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 20篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 22篇 |
1976年 | 20篇 |
1974年 | 17篇 |
1969年 | 13篇 |
排序方式: 共有7306条查询结果,搜索用时 15 毫秒
971.
Ezzedine K Lim HW Suzuki T Katayama I Hamzavi I Lan CC Goh BK Anbar T Silva de Castro C Lee AY Parsad D van Geel N Le Poole IC Oiso N Benzekri L Spritz R Gauthier Y Hann SK Picardo M Taieb A;Vitiligo Global Issue Consensus Conference Panelists 《Pigment cell & melanoma research》2012,25(3):E1-13
During the 2011 International Pigment Cell Conference (IPCC), the Vitiligo European Taskforce (VETF) convened a consensus conference on issues of global importance for vitiligo clinical research. As suggested by an international panel of experts, the conference focused on four topics: classification and nomenclature; definition of stable disease; definition of Koebner's phenomenon (KP); and 'autoimmune vitiligo'. These topics were discussed in seven working groups representing different geographical regions. A consensus emerged that segmental vitiligo be classified separately from all other forms of vitiligo and that the term 'vitiligo' be used as an umbrella term for all non-segmental forms of vitiligo, including 'mixed vitiligo' in which segmental and non-segmental vitiligo are combined and which is considered a subgroup of vitiligo. Further, the conference recommends that disease stability be best assessed based on the stability of individual lesions rather than the overall stability of the disease as the latter is difficult to define precisely and reliably. The conference also endorsed the classification of KP for vitiligo as proposed by the VETF (history based, clinical observation based, or experimentally induced). Lastly, the conference agreed that 'autoimmune vitiligo' should not be used as a separate classification as published evidence indicates that the pathophysiology of all forms of vitiligo likely involves autoimmune or inflammatory mechanisms. 相似文献
972.
DS Kim DR Lee HS Kim JE Yoo SJ Jung BY Lim J Jang HC Kang S You DY Hwang JW Leem TS Nam SR Cho DW Kim 《PloS one》2012,7(7):e39715
Homogeneous culture of neural precursor cells (NPCs) derived from human pluripotent stem cells (hPSCs) would provide a powerful tool for biomedical applications. However, previous efforts to expand mechanically dissected neural rosettes for cultivation of NPCs remain concerns regarding non-neural cell contamination. In addition, several attempts to purify NPCs using cell surface markers have not demonstrated the expansion capability of the sorted cells. In the present study, we show that polysialic acid-neural cell adhesion molecule (PSA-NCAM) is detected in neural rosette cells derived from hPSCs, and employ PSA-NCAM as a marker for purifying expandable primitive NPCs from the neural rosettes. PSA-NCAM-positive NPCs (termed hNPC(PSA-NCAM+)) were isolated from the heterogeneous cell population of mechanically harvested neural rosettes using magnetic-based cell sorting. The hNPC(PSA-NCAM+) extensively expressed neural markers such as Sox1, Sox2, Nestin, and Musashi-1 (80~98% of the total cells) and were propagated for multiple passages while retaining their primitive characteristics in our culture condition. Interestingly, PSA-NCAM-negative cells largely exhibited characteristics of neural crest cells. The hNPC(PSA-NCAM+) showed multipotency and responsiveness to instructive cues towards region-specific neuronal subtypes in vitro. When transplanted into the rat striatum, hNPC(PSA-NCAM+) differentiated into neurons, astrocytes, and oligodendrocytes without particular signs of tumorigenesis. Furthermore, Ki67-positive proliferating cells and non-neural lineage cells were rarely detected in the grafts of hNPC(PSA-NCAM+) compared to those of neural rosette cells. Our results suggest that PSA-NCAM-mediated cell isolation provides a highly expandable population of pure primitive NPCs from hPSCs that will lend themselves as a promising strategy for drug screening and cell therapy for neurodegenerative disorders. 相似文献
973.
Lee JH Kang GB Lim HH Jin KS Kim SH Ree M Park CS Kim SJ Eom SH 《Journal of molecular biology》2008,376(2):308-316
GluR0 from Nostoc punctiforme (NpGluR0) is a bacterial homologue of the ionotropic glutamate receptor (iGluR). We have solved the crystal structure of the ligand-binding core of NpGluR0 in complex with l-glutamate at a resolution of 2.1 Å. The structure exhibits a noncanonical ligand interaction and two distinct subunit interfaces. The side-chain guanidium group of Arg80 forms a salt bridge with the γ-carboxyl group of bound l-glutamate: in GluR0 from Synechocystis (SGluR0) and other iGluRs, the equivalent residues are Asn or Thr, which cannot form a similar interaction. We suggest that the local positively charged environment and the steric constraint created by Arg80 mediate the selectivity of l-glutamate binding by preventing the binding of positively charged and hydrophobic amino acids. In addition, the NpGluR0 ligand-binding core forms a new subunit interface in which the two protomers are arranged differently than the known iGluR and SGluR0 dimer interfaces. The significance of there being two different dimer interfaces was investigated using analytical ultracentrifugation analysis. 相似文献
974.
Yeom JS Kim ES Lim KJ Oh JH Sohn MJ Yoo SB Kim E Bae I Jung YJ Park JW 《The Journal of parasitology》2008,94(6):1410-1414
The antibody levels against the C-terminal region of the merozoite surface protein 1 of Plasmodium vivax (PvMSP1c) were measured in 276 patients with P. vivax malaria (patient group), 320 malaria-na?ve healthy individuals (control group 1), and 70 malaria-na?ve individuals with various disorders (control group 2) using the immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) and the direct sandwich ELISA. To evaluate the antibody response during relapse, 5 relapsed patients were tested using the IgM capture ELISA. The IgM antibodies were negative in 99.7% of control group 1 and in 100% of control group 2; they were positive in 90.6% of the patient group. The total antibody levels were positive in 88.4% of the patient group with the direct sandwich ELISA. The sera from the second malaria episode, i.e., relapsed patients, were 100% positive on the IgM capture ELISA. The results of this study suggest that the IgM capture ELISA may be a useful diagnostic method for P. vivax malaria for both primary infection and relapse. 相似文献
975.
The intracellular signaling mechanisms that couple transient cerebral ischemia to cell death and neuroprotective mechanisms provide potential therapeutic targets for cardiac arrest. Protein phosphatase (PP)-1 is a major serine/threonine phosphatase that interacts with and dephosphorylates critical regulators of energy metabolism, ionic balance, and apoptosis. We report here that PP-1I , a major regulated form of PP-1, is activated in brain by approximately twofold in vivo following cardiac arrest and resuscitation in a clinically relevant pig model of transient global cerebral ischemia and reperfusion. PP-1I purified to near homogeneity from either control or ischemic pig brain consisted of the PP-1 catalytic subunit, the inhibitor-2 regulatory subunit, as well as the novel constituents 14-3-3γ, Rab GDP dissociation protein β, PFTAIRE kinase, and C-TAK1 kinase. PP-1I purified from ischemic brain contained significantly less 14-3-3γ than PP-1I purified from control brain, and purified 14-3-3γ directly inhibited the catalytic subunit of PP-1 and reconstituted PP-1I . These findings suggest that activation of brain PP-1I following global cerebral ischemia in vivo involves dissociation of 14-3-3γ, a novel inhibitory modulator of PP-1I . This identifies modulation of PP-1I by 14-3-3 in global cerebral ischemia as a potential signaling mechanism-based approach to neuroprotection. 相似文献
976.
977.
Due to the introduction of exotic honey bee (Apis mellifera L.) diseases in the eastern states, the borders of the state of Western Australia were closed to the import of bees for breeding and other purposes > 25 yr ago. To provide genetically improved stock for the industry, a closed population breeding program was established that now provides stock for the majority of Western Australian beekeepers. Given concerns that inbreeding may have resulted from the closed population breeding structure, we assessed the genetic diversity within and between the breeding lines by using microsatellite and mitochondrial markers. We found that the breeding population still maintains considerable genetic diversity, despite 25 yr of selective breeding. We also investigated the genetic distance of the closed population breeding program to that of beekeepers outside of the program, and the feral Western Australian honey bee population. The feral population is genetically distinct from the closed population, but not from the genetic stock maintained by beekeepers outside of the program. The honey bees of Western Australia show three mitotypes, originating from two subspecies: Apis mellifera ligustica (mitotypes C1 and M7b) and Apis mellifera iberica (mitotype M6). Only mitotypes C1 and M6 are present in the commercial populations. The feral population contains all three mitotypes. 相似文献
978.
Tan AT Loggi E Boni C Chia A Gehring AJ Sastry KS Goh V Fisicaro P Andreone P Brander C Lim SG Ferrari C Bihl F Bertoletti A 《Journal of virology》2008,82(22):10986-10997
Repertoire composition, quantity, and qualitative functional ability are the parameters that define virus-specific T-cell responses and are linked with their potential to control infection. We took advantage of the segregation of different hepatitis B virus (HBV) genotypes in geographically and genetically distinct host populations to directly analyze the impact that host and virus variables exert on these virus-specific T-cell parameters. T-cell responses against the entire HBV proteome were analyzed in a total of 109 HBV-infected subjects of distinct ethnicities (47 of Chinese origin and 62 of Caucasian origin). We demonstrate that HBV-specific T-cell quantity is determined by the virological and clinical profiles of the patients, which outweigh any influence of race or viral diversity. In contrast, HBV-specific T-cell repertoires are divergent in the two ethnic groups, with T-cell epitopes frequently found in Caucasian patients seldom detected in Chinese patients. In conclusion, we provide a direct biological evaluation of the impact that host and virus variables exert on virus-specific T-cell responses. The discordance between HBV-specific CD8 T-cell repertoires present in Caucasian and Chinese subjects shows the ability of HLA micropolymorphisms to diversify T-cell responses and has implications for the rational development of therapeutic and prophylactic vaccines for worldwide use. 相似文献
979.
Guk-Hyun Suh Tai-Young Hur Sun Lim Sang-Min Shin Jungkee Kwon Shin-Hyeong Cho Chai-Yong Lee Sung-Shik Shin 《The Korean journal of parasitology》2008,46(4):273-278
Mites in the genus Chorioptes cause a mild form of skin disease in both domestic and wild ruminants. In July 2006, dermatitis characterized by alopecia, marked lichenification, accumulation of crust, and fissuring was recognized in 14 out of 200 Holstein dairy cattle raised in the cattle farm of the National Institute of Animal Science in Cheonan, Republic of Korea. Skin lesions were distributed mainly over the tail base, and sacral and perineal regions. Microscopic examinations of skin scraping samples from severely affected areas revealed numerous mites of all developmental stages. Morphologically, pedicels of the mites were short and unjointed. The tarsal suckers occurred on the pedicels of all the legs in the male worm and on the first, second, and fourth pair of legs in the adult female worm. A single long seta at the tarsus of legs III and the length of legs II being about twice as long as legs IV in adult male mites were observed. Arising anterior to the inner-most spatulate seta was a short seta with an average of 26.4 ± 5.8 µm in length. Also, the length of setae #4 on the opisthosomal lobes was relatively short. Based on these observations, the mites were identified as Choriptes texanus. Although the chorioptic mange may not influence the mortality rate in the affected farm, reports indicate that a decline in milk production can be observed. This is the first report of chorioptic infestation in a cattle farm from Korea. 相似文献
980.
Lim DS Choi KJ Guk SM Chai JY Park IY Park YK Seo M 《The Korean journal of parasitology》2008,46(2):87-90
Gynaecotyla squatarolae (Digenea: Microphallidae) adult flukes were recovered from experimental chicks at day 4-6 post-infection and their tegumental ultrastructure was observed with a scanning electron microscopy. They were pyriform in shape, and their anterior halves were concaved ventrally. The whole body surface was covered with tegumental spines, which were wide and 16-17 digitated between oral and ventral suckers. The density of spines and number of digits decreased posteriorly. The oral sucker was subterminal and the excretory pore was at the posterior end of the worm. Two ventral suckers were similar in appearance and protruded near midline of the worm. The genital atrium was dextral to the small ventral sucker. The dorsal surface was covered with tegumental spines, but the spines were sparser than on the ventral surface. On the middle portion of the dorsal surface, a small opening presumed to be the Laurer's canal was seen. From these findings, it has been confirmed that the adult G. squatarolae has unique characteristics in the surface ultrastructure. 相似文献