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31.
本文根据吴征镒教授对中国种子植物属分市区类型研究结果,研制出定量化研究区域性种子植物区系的电子计算机程序,应用本程序可完成某区系的分布区类型统计分析,科属组成分析和与其它地区以共有属关系构建的相似性系数的谁知盘中计算,同时可大量节省研究人员的劳动强度和时间,对提高研究水平有一定的效果。 相似文献
32.
低农药残留量的乌龙茶种质资源筛选研究 总被引:2,自引:0,他引:2
以福建省武夷山茶叶科学研究所鸟龙茶种质资源圃120份资源为试验材料,依外部形态特征初步筛选出31份比较有希望的品种(系)。将联苯菊酯、甲氰菊酯、氯氰菊酯和噻嗪酮4种农药喷施于这31份资源,7d后采摘鲜叶,烘干固样。用气相色谱法分析检测31份品种(系)鲜叶中4种农药的残留量,筛选出低联苯菊酯、低甲氰菊酯、低氯氰菊酯和低噻嗪酮残留量的乌龙茶特异资源各5、4、3和7份。 相似文献
33.
Doo Nam Kim Timothy M. Jacobs Brian Kuhlman 《Protein science : a publication of the Protein Society》2016,25(3):702-710
β‐sheets often have one face packed against the core of the protein and the other facing solvent. Mutational studies have indicated that the solvent‐facing residues can contribute significantly to protein stability, and that the preferred amino acid at each sequence position is dependent on the precise structure of the protein backbone and the identity of the neighboring amino acids. This suggests that the most advantageous methods for designing β‐sheet surfaces will be approaches that take into account the multiple energetic factors at play including side chain rotamer preferences, van der Waals forces, electrostatics, and desolvation effects. Here, we show that the protein design software Rosetta, which models these energetic factors, can be used to dramatically increase protein stability by optimizing interactions on the surfaces of small β‐sheet proteins. Two design variants of the β‐sandwich protein from tenascin were made with 7 and 14 mutations respectively on its β‐sheet surfaces. These changes raised the thermal midpoint for unfolding from 45°C to 64°C and 74°C. Additionally, we tested an empirical approach based on increasing the number of potential salt bridges on the surfaces of the β‐sheets. This was not a robust strategy for increasing stability, as three of the four variants tested were unfolded. 相似文献
34.
Mitigation under Section 404 of the Clean Water Act: where it comes from, what it means 总被引:2,自引:0,他引:2
The requirement to mitigate impacts to wetlands and streams is a frequently misunderstood policy with a long and complicated
history. We narrate the history of mitigation since the inception of the Clean Water Act Section 404 permit program in 1972,
through struggles between the US Environmental Protection Agency and the US Army Corps of Engineers, through the emerging
importance of wetland conservation on the American political landscape, and through the rise of market-based approaches to
environmental policy. Mitigation, as it is understood today, was not initially foreseen as a component of the Section 404
permitting program, but was adapted from 1978 regulations issued by the Council on Environmental Quality as a way of replacing
the functions of filled wetlands where permit denials were unlikely. EPA and the Corps agreed in 1990 to define mitigation
as the three steps of avoidance, minimization, and compensation, principles which must be applied to permit decisions in the
form of the environmental criteria in EPA’s 404(b)(1) Guidelines. Through the 1980s and 1990s, the compensation component
of mitigation has become nearly the sole focus of mitigation policy development, and has been the subject of numerous guidance
documents and memoranda since 1990. Avoidance and minimization have received far less policy attention, and this lack of policy
development may represent a missed opportunity to implement effective wetland conservation.
相似文献
Morgan RobertsonEmail: |
35.
Cyndi Kuehler Alan Lieberman Paul Oesterle Tracey Powers Marla Kuhn Joseph Kuhn Jay Nelson Tom Snetsinger Christina Herrmann Peter Harrity Erik Tweed Steve Fancy Bethany Woodworth Tom Telfer 《Zoo biology》2000,19(4):263-277
From 1995 to 1999, two species of endemic Hawaiian thrushes, `Oma`o (Myadestes obscurus) and Puaiohi (M. palmeri), were captive‐reared and re‐introduced into their historic range in Hawai`i by The Peregrine Fund, in collaboration with the U.S. Geological Survey–Biological Resources Division (BRD) and the Hawai`i State Department of Land and Natural Resources. This paper describes the management techniques that were developed (collection of wild eggs, artificial incubation, hand‐rearing, captive propagation, and release) with the non‐endangered surrogate species, the `Oma`o; techniques that are now being used for recovery of the endangered Puaiohi. In 1995 and 1996, 29 viable `Oma`o eggs were collected from the wild. Of 27 chicks hatched, 25 were hand‐reared and released into Pu`u Wa`awa`a Wildlife Reserve. Using the techniques developed for the `Oma`o, a captive propagation and release program was initiated in 1996 to aid the recovery of the endangered Puaiohi. Fifteen viable Puaiohi eggs were collected from the wild (1996–1997) to establish a captive breeding flock to produce birds for re‐introduction. These Puaiohi reproduced for the first time in captivity in 1998 (total Puaiohi chicks reared in captivity 1996–1998 = 41). In 1999, 14 captive‐bred Puaiohi were re‐introduced into the Alaka`i Swamp, Kaua`i. These captive‐bred birds reproduced and fledged seven chicks in the wild after release. This is the first endangered passerine recovery program using this broad spectrum of management techniques (collection of wild eggs, artificial incubation, hand‐rearing, captive‐breeding, and release) in which re‐introduced birds survived and bred in the wild. Long‐term population monitoring will be published separately [BRD, in preparation]. Zoo Biol 19:263–277, 2000. © 2000 Wiley‐Liss, Inc. 相似文献
36.
The hydrodynamic properties of macromolecules and bioparticles, represented by bead models, can be calculated using methods
implemented in the computer routine HYDRO. Recently, a new computer routine, SOLPRO, has been presented for the calculation
of various SOLution PROperties. These include (1) time-dependent electro-optic and spectroscopic properties related to rotational
diffusion, (2) non-dynamic properties like scattering curves, and (3) dimensionless quantities that combine two or more solution
properties in a form which depends on the shape of the macromolecule but not on its size. In the present work we describe
the inclusion of more of those types of properties in a new version of SOLPRO. Particularly, we describe the calculation of
relaxation rates in nuclear magnetic resonance (NMR). For dipolar coupling, given the direction of the dipole the program
calculates values of the spectral density, from which the NMR relaxation times can be obtained. We also consider scattering-related
properties, namely the distribution of distances for the bead model, which is directly related to the angular dependence of
scattered intensity, and the particle's longest distance. We have devised and programmed a procedure to calculate the covolume
of the bead model, related to the second virial coefficient and, in general, to the concentration dependence of solution properties.
Various shape-dependent dimensionless quantities involving the covolume are calculated. In this paper we also discuss some
aspects, namely bead overlapping and hydration, that are not explicitely included in SOLPRO, but should be considered by the
user.
Received: 25 May 1998 / Revised version: 30 July 1998 / Accepted: 30 July 1998 相似文献
37.
Matthew J. Coussens Courtney Corman Ashley L. Fischer Jack Sago John Swarthout 《Journal of visualized experiments : JoVE》2011,(58)
RNA interference (RNAi) is an intrinsic cellular mechanism for the regulation of gene expression. Harnessing the innate power of this system enables us to knockdown gene expression levels in loss of gene function studies.There are two main methods for performing RNAi. The first is the use of small interfering RNAs (siRNAs) that are chemically synthesized, and the second utilizes short-hairpin RNAs (shRNAs) encoded within plasmids 1. The latter can be transfected into cells directly or packaged into replication incompetent lentiviral particles. The main advantages of using lentiviral shRNAs is the ease of introduction into a wide variety of cell types, their ability to stably integrate into the genome for long term gene knockdown and selection, and their efficacy in conducting high-throughput loss of function screens. To facilitate this we have created the LentiPlex pooled shRNA library.The MISSION LentiPlex Human shRNA Pooled Library is a genome-wide lentiviral pool produced using a proprietary process. The library consists of over 75,000 shRNA constructs from the TRC collection targeting 15,000+ human genes 2. Each library is tested for shRNA representation before product release to ensure robust library coverage. The library is provided in a ready-to-use lentiviral format at titers of at least 5 x 108 TU/ml via p24 assay and is pre-divided into ten subpools of approximately 8,000 shRNA constructs each. Amplification and sequencing primers are also provided for downstream target identification.Previous studies established a synergistic antitumor activity of TRAIL when combined with Paclitaxel in A549 cells, a human lung carcinoma cell line 3, 4. In this study we demonstrate the application of a pooled LentiPlex shRNA library to rapidly conduct a positive selection screen for genes involved in the cytotoxicity of A549 cells when exposed to TRAIL and Paclitaxel. One barrier often encountered with high-throughput screens is the cost and difficulty in deconvolution; we also detail a cost-effective polyclonal approach utilizing traditional sequencing. 相似文献
38.
【背景】脂肪酶是一类特殊的酯键水解酶,广泛应用于工业化生产中,微生物是工业脂肪酶的主要来源。瘤胃中微生物种类繁多、数量庞大,已有关于瘤胃微生物产纤维素酶的报道,尚无产脂肪酶瘤胃微生物的分离筛选报道。【目的】从牦牛瘤胃中分离筛选出能够产脂肪酶的微生物,并进行菌株鉴定及其酶学性质的研究。【方法】以橄榄油为唯一碳源,通过中性红油脂平板进行初步筛选后,用改进铜皂-分光光度法测定酶活力进行复筛;再经形态学观察、生理生化实验和16S rRNA基因序列分析进行菌种鉴定;研究3种脂肪酶的最适作用温度、pH值及金属离子、有机溶剂和表面活性剂对酶活力的影响。【结果】筛选出6株酶活力较高的菌株,其中3株为液化沙雷氏菌,2株为白地霉,1株为卷枝毛霉。脂肪酶的酶学性质研究表明:液化沙雷氏菌、白地霉和卷枝毛霉所产脂肪酶的最适作用温度为45、35和40°C;最适pH为8.0、7.0和7.0;Ca2+和Mg2+对3种脂肪酶均有激活作用;Zn2+对3种脂肪酶有不同程度的抑制作用,EDTA、SDS可使3种脂肪酶失活;3种脂肪酶对丙三醇的耐受力较高,卷枝毛霉脂肪酶对甲醇、乙醇、丙酮的耐受力较高。【结论】从牦牛瘤胃中分离出3种产脂肪酶的微生物,且证实瘤胃微生物在脂肪酶研究方面具有较高的价值。 相似文献
39.
The global impact of the converging dual epidemics of tuberculosis (TB) and human immunodeficiency virus (HIV) is one of the
major public health challenges of our time. The World Health Organization (WHO) reports 9.2 million new cases of TB in 2006
of whom 7.7% were HIV-infected. Tuberculosis is the most common opportunistic infection in HIV-infected patients as well as
the leading cause of death. Further, there has been an increase in rates of drug resistant tuberculosis, including multi-drug
(MDRTB) and extensively drug resistant TB (XDRTB), which are difficult to treat and contribute to increased mortality. The
diagnosis of TB is based on sputum smear microscopy, a 100-year old technique and chest radiography, which has problems of
specificity. Extra-pulmonary, disseminated and sputum smear negative manifestations are more common in patients with advanced
immunosuppression. Newer diagnostic tests are urgently required that are not only sensitive and specific but easy to use in
remote and resource-poor settings. Treatment of HIV-TB co-infection is complex and associated with high pill burden, overlapping
drug toxicities, risk of immune reconstitution inflammatory syndrome (IRIS) and challenges related to adherence. From a programmatic
point of view, screening of all HIV-infected persons for tuberculosis and vice-versa will help identify co-infected patients
who require treatment for both infections. This requires good coordination and communication between the TB and AIDS control
programs, in India. 相似文献
40.
Elizabeth L. Turner Siham Sikander Omer Bangash Ahmed Zaidi Lisa Bates John Gallis Nima Ganga Karen O’Donnell Atif Rahman Joanna Maselko 《Trials》2016,17(1)
BackgroundThe negative effects of perinatal depression on the mother and child start early and persist throughout the lifecourse (Lancet 369(9556):145–57, 2007; Am J Psychiatry 159(1):43-7, 2002; Arch Dis Child 77(2):99–101, 1997; J Pak Med Assoc 60(4):329; J Psychosoma Res 49(3):207–16, 2000; Clin Child Fam Psychol Rev 14(1):1–27, 2011). Given that 10–35 % of children worldwide are exposed to perinatal depression in their first year of life (Int Rev Psychiatry 8(1):37–54, 1996), mitigating this intergenerational risk is a global public health priority (Perspect Public Health 129(5):221–7, 2009; Trop Med Int Health 13(4):579–83, 2008; Br Med Bull 101(1):57–79, 2012). However, it is not clear whether intervention with depressed women can have long-term benefits for the mother and/or her child. We describe a study of the effectiveness of a peer-delivered depression intervention delivered through 36 postnatal months, the Thinking Healthy Program Peer-delivered PLUS (THPP+) for women and their children in rural Pakistan.Methods/designThe THPP+ study aims are: (1) to evaluate the effects of an extended 36-month perinatal depression intervention on maternal and index child outcomes using a cluster randomized controlled trial (c-RCT) and (2) to determine whether outcomes among index children of perinatally depressed women in the intervention arm converge with those of index children born to perinatally nondepressed women. The trial is designed to recruit 560 pregnant women who screened positive for perinatal depression (PHQ-9 score ≥10) from 40 village clusters, of which 20 receive the THPP+ intervention. An additional reference group consists of 560 perinatally nondepressed women from the same 40 clusters as the THPP+ trial. The women in the nondepressed group are not targeted to receive the THPP+ intervention; but, by recruiting pregnant women from both intervention and control clusters, we are able to evaluate any carryover effects of the THPP+ intervention on the women and their children. Perinatally depressed women in the THPP+ intervention arm receive bimonthly group-based sessions. Primary outcomes are 3-year maternal depression and 3-year child development indicators. Analyses are intention-to-treat and account for the clustered design.DiscussionThis trial, together with the reference group, has the potential to further our understanding of the early developmental lifecourse of children of both perinatally depressed and perinatally nondepressed women in rural Pakistan and to determine whether intervening with women’s depression in the perinatal period can mitigate the negative effects of maternal depression on 36-month child development.