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171.
Mendel's work in hybridization is ipso facto a study in inheritance. He is explicit in his interest to formulate universal generalizations, and at least in the case of the independent segregation of traits, he formulated his conclusions in the form of a law. Mendel did not discern, however, the inheritance of traits from that of the potential for traits. Choosing to study discrete non-overlapping traits, this did not hamper his efforts. 相似文献
172.
Merete Grung Frances M. L. D'Souza Michael Borowitzka Synnøve Liaaen-Jensen 《Journal of applied phycology》1992,4(2):165-171
Aplanospores ofHaematococcus pluvialis MUR 145 contained 0.7% carotenoids (dry wt. basis) consisting of β,β-carotene (5% of total carotenoid), echinenone (4%),
canthaxanthin (4%), (3S,3′S)-astaxanthin diester (34%), (3S,3′S)-astaxanthin monoester (46%), (3S,3′S)-astaxanthin (1%) and (3R,3′R,6′R)-lutein (6%).
The astaxanthin esters were examined by TLC and HPLC and VIS,1H NMR and mass spectra recorded. Their chirality was determined by the camphanate method (Vecchi & Müller, 1979) after anaerobic
hydrolysis.
The tough cell wall of the aplanospores required enzymatic treatment prior to pigment extraction. The potential use of this
microalga as a feed ingredient in aquaculture is discussed briefly. 相似文献
173.
ACladosporium species produced large amounts of cellulase enzyme components when grown in shake-culture with medium containing carboxymethylcellulose. There was significantly less activity when Avicel, filter paper or cotton were used as substrates. KNO3 was better than NH4Cl or urea for the production of cellulase. Tween 80 at 0.1% (w/v) increased the production of cellulase by 1.5 to 4.5-fold. All the cellulase components were optimally active in the assay at pH 5.0 and 60°C. 相似文献
174.
The potato has tremendous potential as a transgenic crop and is a good model system by which to analyse metabolic regulation
and gene expression. The potato’s difficult genetics, but ease of genetic transformation and its clonal means of propagation
make it ideal for applied agricultural molecular genetics. Thus, the next 4 years promise to put the potato (with a diversity
of transgenic constructs expressed) in the limelight as many of the first transgenic agricultural products enter the marketplace. 相似文献
175.
M. K. Chandrashekaran G. Marimuthu R. Subbaraj P. Kumarasamy M. S. Ramkumar K. Sripathi 《Journal of biosciences》1991,16(3):97-101
Several bodily functions in humans vary on a 24 h pattern and most of these variations persist with a circadian period ofca 25 h when subjects are studied under conditions of social and temporal isolation. We report in this paper that the estimates
of short time intervals (TE) of 2 h are strongly coupled to the circadian rhythm in sleepwakefulness. There is a linear correlation
between the number of hours humans stay awake (α) and their estimation of 2 h intervals. The coupling of TE to α appears to
obtain only under conditions of physical well-being. 相似文献
176.
When a new strain of Pseudomonas aeruginosa was grown aerobically and then transferred to anaerobic conditions, cells reduced NO
3
–
quantitatively to NO
2
–
in NO
3
–
-respiration. In the absence of nitrate, NO
2
–
was immediately reduced to NO or N2O but not to N2 indicating that NO
2
–
-reductase but not N2O-reductase was active. The formation of the products NO or N2O depended on the pH in the medium and the concentration of NO
2
–
present. When P. aeruginosa was grown anaerobically for at least three davs N2O-reductase was also active. Such cells reduced NO to N2 via N2O. The new strain generated a H+-gradient and grew by reducing N2O to N2 but not by converting NO to N2O. For comparison, Azospirillum brasilense Sp7 showed the same pattern of NO-reduction. In contrast, Paracoccus denitrificans formed 3.5 H+/NO during the reduction of NO to N2O in oxidant pulse experiments but could not grow in the presence of NO. Thus the NO-reduction pattern in P. denitrificans on one side and P. aeruginosa and A. brasilense on the other was very different. The mechanistic implications of such differences are discussed. 相似文献
177.
T. G. Bromage 《Human Evolution》1991,6(2):165-175
This comunication has two primary aims concerned with mineralized tissue biology (e.g. hard tissue biology of bone and tooth)
research in human evolutionary studies: First, to introduce the literature and the methods (at the time of this symposium)
so that one has an idea of the nature of this research and where one can go for details of the methodologies, etc; Second
— and of primary concern here — to discuss issues that have come to light as a result of these studies mainly because of its
recent beginnings as a subfield within paleoanthropology.
Issues related to skeletal studies include; 1) whether different cortical surface pattens and bone tissue types influence
the appearance and interpretation of bone growth activity states; 2) if SEM analyses of cortical surfaces in fossil hominids
allow one to construct meaningful representations of remodeling patterns; 3) whether these representations can be used in
phylogenetic arguments; and 4) how intraspecific variability would affect these issues. Issues related to dental studies include:
1) the relationship between the rate and pattern of eraly hominid dental development; 2) experimental support for the calibration
of eraly hominid dental developmental rates; and 3) whether replica techniques are suitable for microanatomical studies of
these sorts. 相似文献
178.
Personnel records kept by military units of American colonials during the French and Indian War (1755-1763) are analyzed for relationships between environmental factors and stature. A robust American economy and direct access to high-quality food were apparently critical to tallness of this white American male sample. American-born men were taller at all ages than those who had migrated from Europe. January temperatures, rural versus urban birth, and ethnicity also showed stature relationships within the American-born group; thermal effects were by far the strongest of the non-nutritional factors. 相似文献
179.
The relationship between specific environmental factors as independent variables and temporal changes in phytoplankton community
structure in the Vaal River (a turbid system) during 1984 was investigated by employing different diversity indices. Temporal
changes in community structure reflected temporal changes in certain environmental factors. Phytoplankton diversity, measured
with Shannon-Wie H' and Hurlbert PIE indices, was related firstly to discharge and discharge derived variables (such as SO4, Si, N and P loading) and secondly to turbidity derived variables (such as euphotic zone depth). Discharge appears to be
of prime importance in affecting diversity. Observations were made that shed new light on conditions contributing to the development
of an August peak (dominated by Stephanodiscus hantzschii fo. tenuis and Micractinium pusillum) in phytoplankton concentration. Increased environmental stress may reduce the number of sensitive species, thus reducing
interspecific competition between tolerant species which could then exploit the — for them — more favourable conditions resulting
in an increase in their numbers to peak concentrations. 相似文献
180.
Gavril Acălugăriţei 《Acta biotheoretica》1986,35(1-2):107-121
The object of this paper is to present an original classification of ontogenetic reproduction. The main general criterion used is the degree and type of phylogenetic differentiation. In relation to this criterion, criteria are given for the classification of the fundamental types of ontogenetic reproduction and for the classification of the types of ontogenetic generation cycles. Between the fundamental types of ontogenetic reproduction and the types of ontogenetic generation cycles there is a hierarchical relationship which shows that the former are components of the latter. Between the well-defined types of ontogenetic reproduction there exist many intermediate types. 相似文献