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排序方式: 共有693条查询结果,搜索用时 15 毫秒
661.
662.
663.
Haneveld JK 《Tijdschrift voor diergeneeskunde》2008,133(17):718-719
664.
665.
In a scientific project 469 slaughter groups originating from 39 farmers with 37.222 pigs in total were investigated concerning the usefulness of the food chain information. A standard statement does not include enough relevant information for the official veterinarian in the slaughterhouse to do a risk-based meat inspection. Even the food chain information for the visual meat inspection, which has certain limits, shows only farms, where the animals are of good health. Groups of fattened pigs with an extreme high rate of mortality and many abnormalities mean a potential risk for food safety. So for a risk-based meat inspection it is affordable to develop information-systems with real mortality and finding rates and the use of drugs on the farm. 相似文献
666.
Palstra AP Guerrero MA de Laak G Klein Breteler JP van den Thillart GE 《Fish physiology and biochemistry》2011,37(2):285-296
The onset of downstream migration of European eels is accompanied by a cessation of feeding and the start of sexual maturation
which stresses the link between metabolism and sexual maturation, also suggesting an important role for exercise. Exercise
has been tested with eels in swim tunnels and was found to stimulate the onset of sexual maturation. In this study, we have
investigated the interplay between migration and maturation in the field during the downstream migration of female silver
eels. Temporal changes in migratory status and sexual maturation among silver eels of the upstream Rhine River system over
3 months of the migration season (August, September and October) were determined in biometrical parameters, plasma 17β-estradiol
and calcium levels, oocyte histology and gonadal fat levels. Furthermore, the ecological relevant parameters age as determined
by otolithometry and health aspects indicated by haematocrit, haemoglobin and swim-bladder parasite load were measured. Silver
eels were estimated to be 14 years old. A strong temporal progression in migratory stage was shown over the months of downstream
migration. Catches probably represented a mix of reproductive migrants and feeding migrants of which the ratio increased over
time. Furthermore, this study confirmed our hypothesis linking the migratory stage to early maturation as indicated by enlargement
of the eyes, oocyte growth and fat deposition in the oocytes, exactly the same changes as found induced by exercise but not
ruling out environmental influences. Migrants show extensive fat uptake by the oocytes, probably stimulated by the swimming
exercise. In addition, at least 83% of the silver eels in this spawning run may have suffered from negative effects of swim-bladder
parasites on their swimming performance. 相似文献
667.
A E Klein J Freiberg S Same M A Carroll 《Journal of the Association of Official Analytical Chemists》1989,72(6):881-882
A new colorimetric method is described for the determination of enzymatic activity of subtilisin in cleaning products. The procedure is more rapid and precise than the casein digestion methods commonly used to assay protease activity. The principle of the colorimetric method depends on the determination rate of p-nitrophenol released on hydrolysis of N-CBZ-L-leucine-p-nitrophenyl ester at pH 8.0 by subtilisin, with correction for any nonenzymatic (spontaneous) hydrolysis of the substrate. Because of the broad range of hydrolytic activity of this enzyme, and the difficulties in predicting its proteolytic activity, this hydrolytic rate was chosen as a general indicator of subtilisin enzyme behavior. The slope for 7 replicate standard curves generated over a 6 week period exhibited a relative standard deviation of 7.5%, and 8.0% for 20 replicates with an enzyme cleaning product. Papain does not interfere with this assay. 相似文献
668.
W.?Dana?FlandersEmail author Mitch?Klein Paige?Tolbert 《Journal of Agricultural, Biological & Environmental Statistics》2005,10(2):246-257
Generalized additive models (GAMs) have become popular in the air pollution epidemiology literature. Two problems, recently
surfaced, concern implementation of these semiparametric models. The first problem, easily corrected, was laxity of the default
convergence criteria. The other, noted independently by Klein, Flanders, and Tolbert, and Ramsay, Burnett, and Krewski concerned
variance estimates produced by commercially available software. In simulations, they were as much as 50% too small. We derive
an expression for a variance estimator for the parametric component of generalized additive models that can include up to
three smoothing splines, and show how the standard error (SE) estimated by this method differs from the corresponding SE estimated
with error in a study of air pollution and emergency room admissions for cardiorespiratory disease. The derivation is based
on asymptotic linearity. Using Monte Carlo experiments, we evaluated performance of the estimator in finite samples. The estimator
performed well in Monte Carlo experiments, in the situations considered. However, more work is needed to address performance
in additional situations. Using data from our study of air pollution and cardiovascular disease, the standard error estimated
using the new method was about 10% to 20% larger than the biased, commercially available standard error estimate. 相似文献
669.
E. A. Henry L. J. Dodge-Murphy G. N. Bigham S. M. Klein 《Water, air, and soil pollution》1995,80(1-4):489-498
A mass balance model was developed to simulate mercury (Hg) cycling in Onondaga Lake, New York. MERC4, a U.S. Environmental Protection Agency model of the physical and biogeochemical transport and transformation of Hg, was modified by the addition of input from two supporting models (Fish Bioenergetics Model 2 and a lake eutrophication model) to model the transport of Hg into and out of plankton and fish. The model calculates the concentrations of total Hg, methylmercury, elemental Hg, and ionic Hg in both dissolved and particulate forms in the water column. The model was calibrated to an extensive data set of temporally and spatially variable Hg concentrations in Onondaga Lake in 1992. In addition to standard transport processes of advection and dispersion included in MERC4, the Onondaga Lake Mercury Model includes remineralization to simulate release of Hg from settling particulates before incorporation into sediment. The model provides an analytical framework for understanding and predicting the behavior of Hg in Onondaga Lake and has potential use in evaluating the relative impact of different source control and remedial alternatives. 相似文献
670.
Maureen M. Jennings Timothy D. Perkins Mark T. Hemmerlein Richard M. Klein 《Water, air, and soil pollution》1992,65(3-4):237-244
A flow-through system for in situ, near real-time, sequential measurements of rainfall pH and depth was developed for monitoring of precipitation in sites lacking electric power. The system is easily fabricated from readily available instruments and materials, portable, relatively inexpensive and requires minimal maintenance. It also operates independently of AC power making it ideal for use in remote areas. Initial field testing of this system on Camels Hump, Vermont, took place over the period of July to August 1990, during which twenty-seven individual storm events were monitored. The system proved to be robust and reliable, providing rainfall pH and depth information with high (programmable) temporal resolution for unattended periods of up to a week. 相似文献