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881.
Summary: Differences in feeding and trophallaxis among castes of the western drywood termite, Incisitermes minor (Hagen), were determined using rubidium (Rb) as a tracer. Both 5th- and 6th-instar nymphs and 3rd- and 4th-instar larvae fed directly on Rb-treated paper and acted as both donors and recipients in trophallactic exchanges with other larvae and nymphs, and as donors for soldiers and alates. Soldiers and alates did not feed on Rb-treated paper suggesting that they do not feed directly on wood and are completely dependent on nymphs for their nutritional needs. Larvae paired with Rb-fed nymphs received the greatest amount of Rb suggesting that there may be a hierarchy of trophallaxis in drywood termites. Transfer efficiency, the percentage of the total Rb intake of donors that is passed to the recipients, ranged from 1.1 % (nymphal donors to alate recipients) to 16.6 % (larval donors to nymphal recipients). 相似文献
882.
Ibervillea lindheimeri is a dioecious member of the Cucurbitaceae whose male flowers possess a number of sex-specific characteristics including eglandular trichomes on the anther connective. A 2-year study (1989 and 1990) was undertaken to assess the potential for sexual selection of anther trichome number as a male floral trait that enhances pollen removal (a male fitness component). Correlation analysis of ten reproductive and floral traits showed that only the mean number of anther trichomes per flower was significantly associated with mean pollen removal per flower. Anther trichomes are two-celled, consisting of a small, caplike, apical cell and a large, bulbous basal cell. The basal cell is under tension and produces a sticky polysaccharide that is forcefully ejected upward when the apical cell is broken off by visiting bees. The sticky polysaccharide accumulates on the bees and aids in adherence of pollen. We propose that there is directional selection on individual males for number of anther trichomes per flower. The more anther trichomes per flower, the more pollen exported, and the greater the likelihood of siring seeds. Males differed significantly in mean number of anther trichomes per flower and were relatively consistent in their rank order over a 2-year period; both are prerequisites for sexual selection to operate. Selection coefficients and differentials for 1989 and 1990 were 0.005 and 0.007, and 0.22 and 0.32, respectively, and suggest moderate to strong directional selection on anther trichome number. 相似文献
883.
The aim of this paper is to survey the economic approach in relation to animal use during Upper Palaeolithic times in Northern
Spain. The animals present in the archaeological record can be separated into main groups, like those present by natural reasons
and those introduced by human groups. Also in the anthropic aported animals, some of them are related to food procurements
and others to economic reasons. Animals like deer, bovids, equids and so on, were mainly related to nutrition, while some
others like mustelids, canids or felines were more related to the obtention of furs or other non-alimentary uses. The analysis
of the “main-six” (red deer, roe deer, big bovids, horse, ibex and wild boar) showed that all of them were used throughout
the Upper Palaeolithic without many changes in time. 相似文献
884.
A reliable marking technique was needed for a mark–release–recapture experiment with adults of Diabrotica speciosa (Germar). Four marking techniques, acrylic paint (spattered or brushed on the surface of the insect); and fluorescent pigments (dusted on surfaces or mixed with diet to produce an ingested marker), were tested. Fluorescent pigment durability for the dusting and ingested techniques was evaluated for laboratory conditions and under simulated field conditions. The impact of the techniques on beetle survival was also assessed. Both acrylic paint techniques caused mobility problems in the beetles, and neither technique lasted for more than 48 h. Both fluorescent pigment techniques were more reliable, but the dusting technique showed a significantly higher mortality than the control, and duration variations between laboratory and field conditions. Use of fluorescent pigments added to the diet was the most reliable technique. This technique allowed the manipulation of the marking period, and provided reliable timing of marker persistence in the field. 相似文献
885.
886.
887.
I Algarra J J Gaforio T Cabrera A Collado F Garrido 《Journal of biological regulators and homeostatic agents》1999,13(2):90-96
The identification of different mechanisms by which tumours escape from the immune system has helped to evaluate the clinical relevance of a variety of phenotypic changes that occur during tumour development. Among them, changes in HLA class I expression play a leading role in the tumour-host environment since HLA class I molecules interact with T lymphocytes for antigen presentation and with NK cells for inhibition/activation of these immune effector cells. Our laboratory has proposed a classification of the altered HLA class I phenotypes frequently found in human tumours, into five major groups. This review focuses on the tumour phenotypes found in primary and metastatic lesions, the molecular mechanisms that give rise to each phenotype and the clinical implications of these findings. 相似文献
888.
Background: Castration resistant prostate cancer (CRPC) is defined clinically as a failure of castration to prevent an increase in circulating hormones which are associated with worsening prostate cancer. Published information on the frequency and characteristics of CRPC patients are lacking. This may be partly because there is no specific code which doctors can use to record CRPC, making research in existing data sources such as the General Practice Research Database (GPRD) difficult. Methods: The aim of this study was to firstly develop a method to accurately and thoroughly identify CRPC patients in the GPRD, using a combination of codes for treatments and diagnostic tests which these patients are likely to have received. Secondly, the anonymised electronic medical records were used to study the identified CRPC patient characteristics, such as age, treatments, comorbidity and expected survival. Results: After comprehensive exploratory research, the final algorithm was selected to identify patients’ assumed recording on the GPRD of either a rising prostate specific antigen (PSA) value (clinical definition of CRPC) or evidence of a switch in treatment after castration. Using the algorithm, over the 1999–2009 study period, 11 600 castrated prostate cancer patients were identified. Of these, 3277 (28%) developed CRPC during the study period, with an incidence rate of 8.3 per 100 person years in castrated prostate cancer patients, and 3.8 per 100 person years in all prostate cancer patients. Mean patient age at CRPC was 76.8 years, and mean survival duration from CRPC status was 13.5 months, and from first prostate cancer diagnosis was 48.2 months. The most common comorbidities among CRPC patients were hypertension, dyspnoea, and anaemia. Conclusions: Sensitivity analyses to test algorithms with differing inclusion criteria suggested that the primary algorithm was robust, reducing bias through missing data, while avoiding ‘false positives’ and retaining clinical credibility. Overall, our study has documented a reliable method for identifying CRPC patients in GPRD, and thus we have been able to characterise these patients more accurately. 相似文献
889.
Khaled K Abu-Amero José M Larruga Vicente M Cabrera Ana M González 《BMC evolutionary biology》2008,8(1):45
Background
Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. These are the two natural passageways that connect both continents: the northern route through the Sinai Peninsula and the southern route across the Bab al Mandab strait. Recent archaeological and genetic evidence have favored a unique southern coastal route. Under this scenario, the study of the population genetic structure of the Arabian Peninsula, the first step out of Africa, to search for primary genetic links between Africa and Eurasia, is crucial. The haploid and maternally inherited mitochondrial DNA (mtDNA) molecule has been the most used genetic marker to identify and to relate lineages with clear geographic origins, as the African Ls and the Eurasian M and N that have a common root with the Africans L3. 相似文献890.